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The cell wall integrity (CWI) signaling pathway regulates yeast cell wall biosynthesis, cell division, and responses to external stress. The cell wall, comprised of a dense network of chitin, β-1,3- and β-1,6- glucans, and mannoproteins, is very thin,

Cotton micronaire is an essential fiber quality attribute that characterizes both fiber maturity and fineness components. Micronaire and other attributes are measured on fiber lint routinely in laboratories under controlled environmental conditions following a well-established high-volume instrument protocol. In this study, the attenuated total reflection Fourier transform infrared spectroscopy, characterizing fundamental group vibrations in fiber cellulose from 4000 to 400 cm−1, and using an attenuated total reflection device, was explored for fiber micronaire assessment, especially for seed cotton locule fibers that were mingled with nonlint materials, and varied in fiber maturity within a naturally variable sample. Partial least squares multivariate regression models and the algorithmic infrared maturity approach were developed and then applied to predict micronaire values of validation samples and independent seed cotton samples for comparison. Unlike partial least squares models that showed worse in the coefficient of determination, bias, and percentage of samples within the 95% agreement range for independent samples than for validation samples, the algorithmic infrared maturity approach indicated a similarity in the coefficient of determination, bias, and percentage of samples within the 95% agreement range between the validation samples and independent samples. In particular, the algorithmic infrared maturity approach avoided the need to re-calibrate the model with new samples. Therefore, the development of a robust and effective Fourier transform infrared technique combined with the infrared maturity approach for rapid laboratory micronaire assessment and distribution demonstrated a great potential for its extension to the early micronaire testing in remote/breeding locations, and also to regular cotton fibers, processed cotton yarns and fabrics. [ABSTRACT FROM AUTHOR]

The infrared spectra of common biodegradable plastics were first collected using attenuated total reflection infrared spectroscopy, and their characteristic functional groups were labeled. A blend of biodegradable plastic and non-degradable plastic was prepared through melt blending and solution blending. The results indicated that a rapid detection method based on infrared spectroscopy was efficient and accurate in the analysis of biodegradable plastics. This study provides useful references for promoting the development of biodegradable plastics and the treatment of plastic pollution. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Processing of Materials / Elektronnaya Obrabotka Materialov is the property of Institute of Applied Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In pharmaceuticals, pseudo-polymorphism, e.g., the existence of hydrate and anhydrous forms, affects their physicochemical characteristics. Therefore, the evaluation of pseudo-polymorphism is one of the most important quality analyses. In this research, we investigate the real-time monitoring of the hydration reaction of theophylline using terahertz attenuated total reflection time domain spectroscopy (THz-attenuated total reflection (ATR)-TDS). We continuously measured a mixture of hydroxypropyl cellulose solution and theophylline anhydrous (TPA) while keeping it pressed to the ATR surface. We observed that the absorption peaks derived from TPA decreased and those derived from theophylline monohydrate (TPM) increased with time, demonstrating that the hydrate reaction of TPA can be monitored. Subsequently, we performed an accurate and quantitative evaluation of the hydration reaction by calculating the temporal changes in the crystal form ratio of TPM based on the changes in its second derivative peak intensity followed by a curve fitting. In addition, we performed real-time monitoring of the reaction using two different pressure mechanisms, finding that using a weight to apply pressure provided better reproducibility than using a screw. This study demonstrates that THz spectroscopy is a useful method for the evaluation of pseudo-polymorphism in pharmaceuticals. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Cotton fiber maturity has been reported as average maturity and maturity distribution in a sample, through measuring the fibers in the way of either an individual fiber cross-section or a longitude of several subsamples by cross-sectional image analysis (IA), advanced fiber information system (AFIS), and Cottonscope method. As a different approach, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy was proposed to estimate fiber maturity (MIR) and maturity distribution at a bundle fiber level on the basis of three MIR (low-, mid-, and high) classifications. Although maturity distributions from IA, AFIS, or Cottonscope measurement are reported, they are not related with high-volume instrument (HVI) and AFIS qualities considerably. Novelty of this study examined the effect of individual three MIR indices and additional MIR differentials on HVI and AFIS qualities in commercial cotton fibers. There were statistically significant and moderate-to-strong correlations between the MIR indices and fiber maturity and fineness measurements, and also moderate correlations between the MIR indices and other fiber qualities (for example, HVI strength). In particular, there was a moderate correlation between MIR readings and one fiber length parameter [AFIS L(n)] or two short fiber content (SFC) properties [AFIS SFC(w) and AFIS SFC(n)]. Meanwhile, MIR differential (D3) was observed to be correlated with HVI strength significantly and strongly. The result indicated the capability of ATR FT-IR spectroscopy for monitoring fiber maturity distribution in commercial cotton fibers and further in understanding fiber quality measurement. [ABSTRACT FROM AUTHOR]

Injection-molded polyoxymethylene (POM) has molecular chains mainly oriented in the injection direction. We investigated the directional dependence of the polarized infrared reflection and attenuated total reflection spectra by rotating the anisotropic POM sample. Because of the strong absorption and large frequency dispersion of the C–O vibration in the main-chain direction, we found phenomena such as shoulder wing generation that resulted from the mixing of optical responses attributed to the vibration in the main chain and that in the direction perpendicular to the main chain. The spectra of the directional dependence can be explained qualitatively because of the anisotropy of the mode with large frequency dispersion. Graphical abstract This is a visual representation of the abstract. [ABSTRACT FROM AUTHOR]

Juice counterfeiting not only affects product quality but also deceives consumers into buying low-quality goods at high prices. Here is explored the feasibility of combining attenuated total reflection–mid-infrared (ATR-MIR) spectroscopy and interval-based partial least squares (PLS) and full-spectrum PLS models for identifying the adulteration of apple juice. A sample set composed of 41 concentrations of diluted juice was prepared. The adulteration concentration was obtained based on the juice spectrum and the corresponding model. The changeable moving window PLS model was shown to provide the best performance and may be an alternative to traditional approaches for quality control of juice. [ABSTRACT FROM AUTHOR]

Sensors based on surface plasmon resonance excited in the scheme of attenuated total reflection (ATR) on thin metal films have undergone a revolution in the visible frequency range. It is possible to study very weak interactions, up to single molecules, using these sensors. Such an approach, which has already become classical, cannot be implemented in the terahertz-frequency range. Terahertz waves barely penetrate metals due to their high dielectric constant, which makes it difficult to maintain resonance at the metal–dielectric interface. One way to overcome this problem is to modify the metal surface with a structure with a characteristic size much smaller than the radiation wavelength. The structured region of the metal behaves as an effective layer of the medium, the permittivity of which is a function of the response of the dielectric and the metal. On these structures, spoof-surface plasmon resonances, which are similar in properties to surface plasmon resonances in the visible range, can be excited. By combining spoof-surface plasmon resonance and attenuated total reflection, it is possible to implement a sensor that, in the future, will make it possible to detect the smallest concentrations and observe small changes in the boundary dielectric medium in the terahertz-frequency range. The excitation of a spoof-surface plasmon resonance is studied using the method of attenuated total reflection on a flat one-dimensional subwavelength grating with gold sputtering in the Otto scheme. For the first time, the angular reflection spectra are measured according to this scheme using monochromatic terahertz radiation from the Novosibirsk free-electron laser (the wavelength is 141 μm). The plasmon resonances observed in the spectra are consistent with the simulation results using COMSOL Multiphysics. [ABSTRACT FROM AUTHOR]

Inductively coupled plasma and microwave digestion are used in this article to analyze various food matrices. Different natural herbs are used in the recipes for the food items that the people of the Middle Eastern part of the world eat; they use these herbs as spices in different proportions. The study examines the potential effects on human health associated with consuming trace and toxic elements, such as Ni, Mn, Pb, Cd, Fe, Zn, Ca, Mg, K, and Na. The targeted spices include sumac, za’atar, black lemon, cumin seed, and kabsa powder; these were used in a variety of recipes for the food items the people of Saudi Arabia eat but not limited to fattier, kabsa, tabbouleh, humus, haysa Al tumreya, and other traditional foods. The herbs were collected from the Saudi Arabian market. For microwave digestion, Merck's ultra-pure nitric acid and 30% hydrogen peroxide were used. For elemental analysis, a highly sophisticated technique of inductively coupled plasma mass spectrometry was applied. The average potassium values in black lemon (Loomi), kabsa powder, cumin seed, za’atar, and sumac were 1,283, 1,248, 1,739, 500, and 500 mg/100 g, respectively. These spices help fulfill the human body’s daily requirements of elemental content.

The molecular basis of bone structure and strength is mineralized collagen fibrils at the submicron scale (∼500 nm). Recent advances in optical photothermal infrared (O-PTIR) spectroscopy allow the investigation of bone composition with unprecedented submicron spatial resolution, which may provide new insights into factors contributing to underlying bone function. Here, we investigated (i) whether O-PTIR-derived spectral parameters correlated to standard attenuated total reflection (ATR) Fourier transform infrared spectroscopy spectral data and (ii) whether O-PTIR-derived spectral parameters, including heterogeneity of tissue, contribute to the prediction of proximal femoral bone stiffness. Analysis of serially demineralized bone powders showed a significant correlation (r = 0.96) between mineral content quantified using ATR and O-PTIR spectroscopy, indicating the validity of this technique in assessing bone mineralization. Using femoral neck sections, the principal component analysis showed that differences between O-PTIR and ATR spectra were primarily attributable to the phosphate ion (PO4) absorbance band, which was typically shifter toward higher wavenumbers in O-PTIR spectra. Additionally, significant correlations were found between hydrogen phosphate (HPO4) content (r = 0.75) and carbonate (CO3) content (r = 0.66) quantified using ATR and O-PTIR spectroscopy, strengthening the validity of this method to assess bone mineral composition. O-PTIR imaging of individual trabeculae at 500 nm pixel resolution illustrated differences in submicron composition in the femoral neck from bones with different stiffness. O-PTIR analysis showed a significant negative correlation (r = –0.71) between bone stiffness and mineral maturity, reflective of newly formed bone being an important contributor to bone function. Finally, partial least squares regression analysis showed that combining multiple O-PTIR parameters (HPO4 content and heterogeneity, collagen integrity, and CO3 content) could significantly predict proximal femoral stiffness (R 2 = 0.74, error = 9.7%) more accurately than using ATR parameters. Additionally, we describe new findings in the effects of bone tissue orientation in the O-PTIR spectra. Overall, this study highlights a new application of O-PTIR spectroscopy that may provide new insights into molecular-level factors underlying bone mechanical competence. Graphical Abstract This is a visual representation of the abstract. [ABSTRACT FROM AUTHOR]

A method for measuring the optical functions of a flat sample made of homogeneous and isotropic material, using attenuated total reflection spectroscopy when there is poor contact between the sample and the internal reflection element is presented. The approach consists in treating the spacing between the internal reflection element and the sample as an adjustable parameter, along with the dispersion model parameters, in the simultaneous fitting of s - and p -polarized spectra obtained when the gap distance is unknown. The method is tested with both synthetic and experimental (polystyrene) spectra. The results demonstrate the method's ability to accurately determine the optical functions even in the presence of a contact problem. Graphical Abstract This is a visual representation of the abstract. [ABSTRACT FROM AUTHOR]

The analytical performance of a compact infrared attenuated total reflection spectrometer using a pyroelectric detector array has been evaluated and compared to a conventional laboratory Fourier transform infrared system for applications in food analysis. Analytical characteristics including sensitivity, repeatability, linearity of the calibration functions, signal-to-noise ratio, and spectral resolution have been derived for both approaches. Representative analytes of relevance in food industries (i.e., organic solvents, fatty acids, and mycotoxins) have been used for the assessment of the performance of the device and to discuss the potential of this technology in food and feed analysis. Graphical Abstract This is a visual representation of the abstract. [ABSTRACT FROM AUTHOR]

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.

Herbal powder preparations (HPPs) are common forms of traditional medicine made by blending the powder of two or more ingredients. The first step to ensure the safety and efficacy of HPPs is to confirm the prescribed ingredients and screen the abnormal ingredients. With the help of attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) imaging or mapping, the particles of different ingredients in an HPP sample can be measured individually. In this way, the overlapped absorption signals of different ingredients in the ATR FT-IR spectrum of the bulk sample can be isolated in the ATR FT-IR spectra of the microscopic particles, which leads to the substantial increase of the specificity and sensitivity of the infrared spectral identification method. The characteristic particles of each ingredient can be identified by the objective comparison of the microscopic ATR FT-IR spectra against the reference spectra based on the correlation coefficients. Since the ATR FT-IR imaging or mapping tests of HPPs are free of the separation preprocess, multiple organic and inorganic ingredients are able to be recognized by a single identification procedure simultaneously rather than by different separation and identification procedures. As an example, the ATR FT-IR mapping method was used in this research to successfully identify three prescribed ingredients and two abnormal ingredients in oral ulcer pulvis, which is a classic HPP for oral ulcer in traditional Chinese medicine. The results show the feasibility of the ATR FT-IR microspectroscopic identification method for the objective and simultaneous identification of the prescribed and abnormal ingredients of HPPs. [ABSTRACT FROM AUTHOR]

Cotton fiber maturity has been determined by cross-sectional image analysis (IA), advanced fiber information system (AFIS), and Cottonscope methods on cotton lint. These methods have reported the results as average maturity and maturity distribution in a sample, through measuring the fibers in the ways of either individual fiber cross-section or longitude of several sub-samples. Previous studies have shown good agreement in maturity for well-prepared samples among these methods, although AFIS is observed to be less sensitive. As a different approach, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy was proposed to measure fiber maturity (M IR) at bundle fiber level. Extending fiber maturity measurement into seed cotton, the FT-IR method might be an option considering such factors as essential cotton seed and visible trash removal, measuring system availability and speed, and also sub-sampling representation in a naturally variable sample. A comparison of fiber M IR average in seed cottons with AFIS maturity ratio (M AFIS) in ginned cotton fibers exhibited a general trend of increasing M AFIS with M IR. On the basis of M IR value, 3- M IR (low-, mid-, and high-) fiber classification analysis implied the distinctions within seed cottons having close M IR average, and among the same cultivar grown at different conditions. Additionally, cultivars with a similar maturity distribution varied in fiber crystallinity (CI IR) distribution, and vice versa. [ABSTRACT FROM AUTHOR]

Micro-Multiple Reflection ATR (CMRATR) spectroscopy is a technique, using specialized equipment, which allows the enhanced sensitivity of multiple reflection ATR analysis of small amounts of liquids in a confined area hitherto reserved for single reflection equipment. This technique has demonstrated a high level of sensitivity, especially when used in conjunction with an evaporative technique. In this work, the technique will be used with a miniature CMRATR accessory, which has the added advantage of compatibility with the smallest current FTIR spectrometers, to analyze pesticides. The results presented here indicate that the CMRATR/evaporative technique can serve as both qualitative and quantitative support to the existing standard methodology. [ABSTRACT FROM AUTHOR]

The integration of a microfluidic chip into terahertz time-domain attenuated total reflection (THz TD-ATR) spectroscopy is highly demanded for the accurate measurement of aqueous samples. Hitherto, however little work has been reported on this regard. Here, we demonstrate a strategy of fabricating a polydimethylsiloxane microfluidic chip (M-chip) suitable for the measurement of aqueous samples, and investigate the effects of its configuration, particularly the cavity depth of the M-chip on THz spectra. By measuring pure water, we find that the Fresnel formulae of two-interface model should be applied to analyze the THz spectral data when the depth is smaller than 210 μm, but the Fresnel formula of one-interface model can be applied when the depth is no less than 210 μm. We further validate this by measuring physiological solution and protein solution. This work can help promote the application of THz TD-ATR spectroscopy in the study of aqueous biological samples.

Comprehensive modeling of non-polarized infrared attenuated total reflection spectrum based on Fresnel equations and wavenumber-dependent dielectric function models of isotropic materials is shown to be a suitable and easy methodology to retrieve optical functions. The scheme is completely general and can be used even for strong dispersion and absorption resonances. Attenuated total reflection spectra in liquid water, measured in the spectral region 100–4400 cm−1 with diamond and germanium as internal reflection elements, were used to illustrate and evaluate the method. The refractive index of water computed from the dispersion analysis is critically compared with literature data. Graphical Abstract [ABSTRACT FROM AUTHOR]

This study presents the first mid-infrared (IR)-based method capable of simultaneously predicting concentrations of individual fatty acids (FAs) and relevant sum parameters in human milk (HM). Representative fat fractions of 50 HM samples were obtained by rapid, two-step centrifugation and subsequently measured with attenuated total reflection IR spectroscopy. Partial least squares models were compiled for the acquired IR spectra with gas chromatography-mass spectrometry (GC-MS) reference data. External validation showed good results particularly for the most important FA sum parameters and the following individual FAs: C12:0 (R2P = 0.96), C16:0 (R2P = 0.88), C18:1cis (R2P = 0.92), and C18:2cis (R2P = 0.92). Based on the obtained results, the effect of different clinical parameters on the HM FA profile was investigated, indicating a change of certain sum parameters over the course of lactation. Finally, assessment of the method's greenness revealed clear superiority compared to GC-MS methods. The reported method thus represents a high-throughput, green alternative to resource-intensive established techniques. [ABSTRACT FROM AUTHOR]

In this study, we demonstrate that drugs in plastic packaging can be identified without being opened using attenuated total reflection terahertz time domain spectroscopy. In this system, the terahertz wave undergoes total internal reflection at the interface between prism and sample, producing an evanescent wave at the interface. The penetration depth of the evanescent waves is larger than the thickness of typical plastic packaging in the sub-terahertz frequency region; therefore, it becomes possible to detect the sample without opening the package. Here, we show that some saccharides samples such as lactose in plastic packaging can be identified using its spectral fingerprint by placing the packaged lactose on the prism. This method has the potential to be used in the non-destructive testing and analysis of a wide variety of samples, such as medicine sachets, to reduce medication dispensing errors in pharmacies.

The possibility of using mid-infrared (IR) spectroscopy in combination with the method of attenuated total reflection (ATR) to analyze the quality of dairy products is shown. The application of chemometrics, in particular the multivariate curve resolution (MCR) algorithm, to the spectral data of the milk drop-drying process allows us to obtain spectra of its individual components, which is potentially useful to make quantitative estimates of the sample composition.

Due to increasing interest in imaging, industrial, and the development of wireless communication operating at THz frequencies, it is crucial to ascertain possible health impacts arising from exposure to THz radiation. This paper reports on the pilot study of transmittance and absorbance spectra of the porcine cornea following THz frequency irradiation at a synchrotron THz/Far-IR beamline. The exposure period was 4 hours. One cornea was exposed to the radiation, with a second cornea acting as a control. An Attenuated Total Reflection (ATR) apparatus was used, and the frequency range of 2.4 to 8 THz was selected to evaluate any changes. It was found that the synchrotron THz radiation intensities are too low to produce induced corneal injury, but may lead to subtle changes in the state of water. Our results suggest that THz spectroscopy is a promising modality for corneal tissue hydration sensing. [ABSTRACT FROM AUTHOR]

Microorganisms are one of the main factors in the deterioration of cultural heritage, in particular art paintings. The antiseptics currently used in painting have significant limitations due to insufficient effectiveness or increased toxicity and interaction with art materials. In this regard, the actual challenge is the search for novel materials that effectively work against microorganisms in the composition with painting materials and do not change their properties. Chitosan has pronounced antimicrobial properties but was not used previously as an antiseptic for paintings. In our study we developed a number of mock layers based on sturgeon glue, supplemented which chitosan (molecular weight 25 kDa or 45 kDa), standard antiseptics for paintings (positive controls) or without additives (negative control). According to Fourier transform infrared spectroscopy and atomic force microscopy, the addition of chitosan did not significantly affect the optical and surface properties of this material. The ability of chitosan to effectively protect paintings was shown after inoculation on the created mock-up layers of 10 fungi-destructors of tempera painting, previously isolated from cultural heritage of the of the 15–16th centuries in the State Tretyakov Gallery, on the created mock layers. Our study demonstrated the principled opportunity of using chitosan in the composition of painting materials to prevent biodeterioration for the first time. [ABSTRACT FROM AUTHOR]

Attenuated total reflection Fourier transform infrared spectroscopy（ATR-FTIR）technology is utilized to quickly identify and detect different fermentation batches for γ-polyglutamic-acid（γ-PGA）. Based on partial least squares discriminant analysis（PLSDA）, five classification models were established to distinguish each batch from other batches, which performed well on several individual evaluation indicators（e.g., accuracy). In order to improve the model performance on all the indicators（e.g., accuracy, precision, sensitivity, etc.）and the model interpretability, three wavenumber selection methods including subwindow permutation analysis（SPA）, competitive adaptive reweighted sampling（CARS）and random frog（RF）were combined with PLSDA to extract key wavenumbers and then established the corresponding classification models. Experimental results show that all the performance indicators of PLSDA combined with wavenumber selection（except CARS-PLSDA）are improved. Additionally, both the model complexity and interpretability are improved. Therefore, ATR-FTIR technology combined with SPA-PLSDA or RF-PLSDA method can realize rapid identification of different γ-PGA fermentation batches. [ABSTRACT FROM AUTHOR]

The behavior of nitrogen in silicon dioxide films on single-crystal silicon substrates was studied by attenuated total reflection (ATR) and time-of-flight secondary ion mass spectrometry. Nitrogen was introduced into a dielectric formed by pyrogenic oxidation at 850°C in an atmosphere of wet oxygen by implantation of N+ ions of energy 40 keV at doses of 2.5·1014 and 1.0·1015 cm–2 followed by rapid thermal annealing at 1000 or 1050°C for 15 s in air. Some of the samples were nitrided during thermal annealing in an N2 atmosphere with the addition of a small amount of O2 at 1200°C for 120 min. It was established that the majority of N atoms diff used during the heat treatments to the SiO2/Si interface and accumulated near the boundary region of the oxide. ATR spectra showed an absorption band with maxima at ~2320 and 2360 cm–1 that was probably due to vibrations of double cumulative bonds of the O=Si=N– type. These bonds formed through the interaction of N with dangling bonds at the Si-dielectric interface, as a result of which uncompensated or strained bonds were replaced by more stable ones. The resulting stronger chemical bonds prevented charge accumulation on the surface of the SiO2/Si interface. [ABSTRACT FROM AUTHOR]

This study develops regression models for predicting blood biochemical data using Fourier-transform infrared spectroscopy (FTIR) analysis. Absorption at specific wavelengths of blood serum is revealed to have strong correlations with biochemical parameters, such as ALT, amylase, AST, protein, bilirubin, Gamma-GT, iron, calcium, uric acid, triglycerides, phosphatase and cholesterol, were shown. The results consistently demonstrate that Random Forest Regression outperforms other models, delivering impressive outcomes for the majority of the analyzed parameters. For some parameters we obtained a coefficient of determination of 0.95 and more (amylase, AST, iron, calcium, protein, uric acid and cholesterol), which makes this approach to be applicable in clinical diagnostics. These findings highlight the potential of FTIR analysis combined with regression models for precise assessment of blood biochemistry., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Attenuated total reflection far-ultraviolet (ATR-FUV) spectra in the 145–250 nm region were studied for four kinds of proteins (two α-helix-rich proteins: bovine serum albumin (BSA) and lysozyme and two β-sheet rich proteins: concanavalin A and γ-globulin) in different solutions (pure water and phosphate buffered saline, or PBS) with different concentrations. All the spectra show a band at 191 nm due to the π–π* transition of amide bonds of the proteins. The wavelength of the band does not change with their second structures, suggesting that the corresponding electronic transition mode is localized and polarized in the direction that is not affected by the difference in the peptide folding. The intensity of the 191 nm band differs with the concentration of salt in the solution, suggesting that the band intensity reflects the adsorption density of a protein on the internal reflection element (IRE) made of a sapphire glass prism. According to the intensity changes of the band at 191 nm, it is revealed that the properties in adsorption are different from one protein to another. It is assumed that there are two types of forces on the protein adsorption: one is that among the molecules and the other is that between a molecule and a substrate. The origin of force includes localized electrostatic polarity and affinity to water. The ions in the solvent give a marked effect on these forces, resulting in the difference in the response to adsorption density against the salt concentration in the solvent. Graphical Abstract [ABSTRACT FROM AUTHOR]

This study introduces the first mid-infrared (IR)–based method for determining the fatty acid composition of human milk. A representative milk lipid fraction was obtained by applying a rapid and solvent-free two-step centrifugation method. Attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy was applied to record absorbance spectra of pure milk fat. The obtained spectra were compared to whole human milk transmission spectra, revealing the significantly higher degree of fatty acid–related spectral features in ATR FT-IR spectra. Partial least squares (PLS)–based multivariate regression equations were established by relating ATR FT-IR spectra to fatty acid reference concentrations, obtained with gas chromatography–mass spectrometry (GC-MS). Good predictions were achieved for the most important fatty acid sum parameters: saturated fatty acids (SAT, R2CV = 0.94), monounsaturated fatty acids (MONO, R2CV = 0.85), polyunsaturated fatty acids (PUFA, R2CV = 0.87), unsaturated fatty acids (UNSAT, R2CV = 0.91), short-chain fatty acids (SCFA, R2CV = 0.79), medium-chain fatty acids (MCFA, R2CV = 0.97), and long-chain fatty acids (LCFA, R2CV = 0.88). The PLS selectivity ratio (SR) was calculated in order to optimize and verify each individual calibration model. All mid-IR regions with high SR could be assigned to absorbances from fatty acids, indicating high validity of the obtained models. Graphical Abstract [ABSTRACT FROM AUTHOR]

Copyright of Forensic Science & Technology is the property of Institute of Forensic Science, Ministry of Public Security and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We present an attenuated total reflection (ATR) correction scheme capable of rectifying ATR spectra while considering the polarization state for arbitrary angles of incidence, provided that this angle exceeds the critical angle for the entire ATR spectrum. Due to its reliance on the weak absorption approximation, it cannot achieve perfect correction of the ATR spectra. However, comprehending its functionality may offer valuable insights into the concept behind the weak absorption approximation. Depending on the specific polarization state of an instrument accessory combination, this correction scheme may outperform the proprietary advanced ATR correction authored by ThermoFisher while being as user-friendly, but in contrast to the latter completely transparent with regard to its functionality. [ABSTRACT FROM AUTHOR]

The chemical composition of recent and fossil organic-walled dinoflagellate cyst walls and its diversity is poorly understood and analyses on single microscopic specimens are rare. A series of infrared spectroscopic experiments resulted in the proposition of a standardized attenuated total reflection micro-Fourier transform infrared-based method that allows the collection of robust data sets consisting of spectra from individual dinocysts. These data sets are largely devoid of nonchemical artifacts inherent to other infrared spectrochemical methods, which have typically been used to study similar specimens in the past. The influence of sample preparation, specimen morphology and size and spectral data processing steps is also assessed within this methodological framework. As a result, several guidelines are proposed which facilitate the collection and qualitative interpretation of highly reproducible and repeatable spectrochemical data. These, in turn, pave the way for a systematic exploration of dinocyst chemistry and its assessment as a chemotaxonomical tool or proxy. Graphical Abstract [ABSTRACT FROM AUTHOR]

An innovative mid-infrared spectroscopic sensor system based on quantum cascade lasers has been developed. The system combines the versatility of substrate-integrated hollow waveguides (IHWGs) with the robustness of attenuated total reflection (ATR) crystals employed as internal reflection waveguides for evanescent field sensing. IHWGs are highly reflective metal structures that propagate infrared (IR) radiation and were used as light pipes for coupling radiation into the ATR waveguide. The combined IHWG-ATR device has been designed such that the utmost stability and robustness of the optical alignment were ensured. This novel assembly enables evanescent field absorption measurements at yet unprecedently harsh conditions, that is, high pressure and temperature. Combining these advantages, this innovative sensor assembly is perfectly suited for taking ATR spectroscopy into the field where the robustness of the assembly and optical alignment is essential. Graphical Abstract [ABSTRACT FROM AUTHOR]

Terahertz (THz) plasmonic sensors has been regarded as exciting advances in biomedical engineering, due to their real-time, label-free, and ultrasensitive monitoring features. But actually, its widespread application remains impeded by poor modulation properties of operating frequency, single amplitude characterization method, and limited to low-loss substances. In the work, an ultraprecision THz sensor is achieved with direct phase readout capacity via combining steerable plasmonic resonance and attenuated total reflection. Interestingly, the oft-neglected THz phase were found to be ideal for plasmonic sensing characterization. Detailed investigation shows that the reflected THz phase exhibits two entirely different jump responses to coupling gap. Remarkably, the Q-factor of phase spectra for optimal coupling gaps, are generally higher than that of fixed coupling gaps, which falls within the range of 9.7–43.4 (4–26 times higher than its counterpart in amplitude measurements) in liquids sensing. The unique phase-jump responses on metasurfaces pave the way for novel THz sensing methods.

A strategy is proposed to achieve wideband tunable perfect plasmonic absorption in graphene nanoribbons by employing attenuated total refraction (ATR) in Otto prism configuration. In this configuration, the Otto prism with a deep-subwavelength dielectric spacer is used to generate tunneling evanescent waves to excite localized plasmons in graphene nanoribbons. The influence of the configuration parameters on the absorption spectra of graphene plasmons is studied systematically, and the key finding is that perfect absorption can be achieved by actively controlling the incident angle of light under ATR conditions, which provides an effective degree of freedom to tune the absorption properties of graphene plasmons. Based on this result, it is further demonstrated that by simultaneously tuning the incident angle and the graphene Fermi energy, the tunable absorption waveband can be significantly enlarged, which is about 3 times wider than the conventional cavity-enhanced configuration. Our proposed strategy to achieve wideband, tunable graphene plasmons could be useful in various infrared plasmonic devices.

This study presents the first mid-infrared (IR)-based method capable of simultaneously predicting concentrations of individual fatty acids (FAs) and relevant sum parameters in human milk (HM). Representative fat fractions of 50 HM samples were obtained by rapid, two-step centrifugation and subsequently measured with attenuated total reflection IR spectroscopy. Partial least squares models were compiled for the acquired IR spectra with gas chromatography-mass spectrometry (GC-MS) reference data. External validation showed good results particularly for the most important FA sum parameters and the following individual FAs: C12:0 (R2P = 0.96), C16:0 (R2P = 0.88), C18:1cis (R2P = 0.92), and C18:2cis (R2P = 0.92). Based on the obtained results, the effect of different clinical parameters on the HM FA profile was investigated, indicating a change of certain sum parameters over the course of lactation. Finally, assessment of the method’s greenness revealed clear superiority compared to GC-MS methods. The reported method thus represents a high-throughput, green alternative to resource-intensive established techniques.

Due to increasing interest in imaging, industrial, and the development of wireless communication operating at THz frequencies, it is crucial to ascertain possible health impacts arising from exposure to THz radiation. This paper reports on the pilot study of transmittance and absorbance spectra of the porcine cornea following THz frequency irradiation at a synchrotron THz/Far-IR beamline. The exposure period was 4 hours. One cornea was exposed to the radiation, with a second cornea acting as a control. An Attenuated Total Reflection (ATR) apparatus was used, and the frequency range of 2.4 to 8 THz was selected to evaluate any changes. It was found that the synchrotron THz radiation intensities are too low to produce induced corneal injury, but may lead to subtle changes in the state of water. Our results suggest that THz spectroscopy is a promising modality for corneal tissue hydration sensing.

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[Display omitted] • Fast, simple and direct determination of GBL in adulterated beverages. • GBL prediction capability statistically comparable in all samples evaluated. • Suitable methodology for in-situ forensic Analytical Chemistry without solvent and reagents. • Developed procedure in good agreement with the principles of Green Analytical Chemistry. • Simplicity in calibration model required. A green partial least square (PLS) attenuated total reflectance infrared spectroscopy (ATR-FTIR) method has been developed for the prediction of the γ-butyrolactone (GBL) in all type of soft and alcoholic beverages. The method involves the use of a drop (less than 5 µL) of sample and a single calibration model based on aqueous and alcoholic solutions of GBL and beverages free from GBL. A selected wavenumber range from 1225 to 1171 cm−1 and from 999 to 972 cm−1 of the second derivative (SD) spectra of samples and standards were employed. The validation set provided root mean square error of prediction (RMSEP) of the order of 300 µg g−1 GBL with a ratio of standard error of performance to standard deviation value (RPD) of 13.4. The prediction of unknown samples not considered in the calibration nor in the validation sets offered accuracy relative errors between −1.0 and 2.9 % GBL. The proposed PLS-FTIR based method allows a fast and direct determination of GBL in all type of beverages, in less than 2 min and avoiding the use of neither reagents nor solvents, without any sample treatment required, being in agreement with the principles of Green Analytical Chemistry. [ABSTRACT FROM AUTHOR]

In the research on application of an optical modulator used for information communication, materials having a large Pockels effect, a refractive index change proportional to the electric-field, are required. It is known that the interfacial water on the surface of transparent oxide electrodes has a giant Pockels coefficient, which is an order of magnitude larger than the solid Pockels crystals practically used. It is important to know the Pockels coefficient of water on not only an oxide surface, but also a metal surface to understand the mechanism of the interfacial Pockels effect of water. However, a method has not yet been established for evaluating the coefficient of water–metal interface. Here we present an evaluation method of the Pockels coefficient of interfacial water on a metal (silver) surface from the spectral shift of the surface plasmon polariton resonance due to electric-field induced refractive index change of the interfacial water. The Pockels coefficient of interfacial water on Ag was evaluated as | r 33 | = 5 ± 1 pm/V, without need for exact knowledge of the thickness of the interfacial layer (electric double layer of water) as long as the penetration depth of the plasmon is larger than the thickness. [ABSTRACT FROM AUTHOR]

The surface‐enhanced Raman scattering (SERS) effect was discovered by Richard Van Duyne et al. in 1977. He and coworkers also first utilized an innovative strategy that used SERS to record spectra on such SERS‐inactive substrate surfaces as n‐gallium arsenide (100) surfaces, which were modified by silver nano‐islands. This nanostructure‐enhanced Raman spectroscopy on flat surfaces (NERSoFS) enabled such SERS applications to be expanded to a variety of materials by virtue of SERS‐active nanostructures such as Au or Ag nanoparticles and shell‐isolated nanoparticles. However, most of such systems, although yielding Raman spectra, produce rather low enhancements, especially when used to record spectra on flat surfaces of SERS‐inactive materials. In this work, along with the direction of Van Duyne's borrowing‐SERS strategy and on the basis of the strategy of cascading optical coupling, we consider a theoretically designed optical configuration, based on an attenuated total reflection‐cascading nanostructure to produce enhanced Raman spectroscopy (ATRc‐NERS) on flat surfaces. This system can effectively harvest the incident light, thereby boosting the local optical field of the incident light and also moderately increasing the radiation field of the Raman‐scattered signals. In this way, one can gain 1–2 additional orders of magnitude in Raman enhancement over present NERSoFS systems both on metallic and nonmetallic flat surfaces, which are otherwise SERS‐inactive. This ATRc‐NERS strategy can potentially be used to develop ultrasensitive and versatile tools for surface science, material science, catalysis, electrochemistry, and micro‐electronics and micro‐LED industries. [ABSTRACT FROM AUTHOR]

Multiple Fano resonances (FRs) and plasmon-induced transparency (PIT) are observed and analyzed in one-dimensional photonic crystals (1D-PhCs) coupled surface plasmon polariton (SPP) structure under the attenuated total reflection (ATR) configuration. Coupling between the excited guided modes of 1D-PhCs and SPP mode leads to Fano type resonances which are confirmed by numerical calculation. Magnetic field distributions at the resonances are also presented to verify the existence of multiple FRs. It is demonstrated that the position and the linewidth of the FRs can be engineered by the structural parameters. Moreover, the position of FRs can be obtained at any desired wavelengths in the near-infrared (NIR) range. These results pave a new way for the development of multiband reflectors working in NIR based on FR. [ABSTRACT FROM AUTHOR]

Corneal collagen cross-linking (CXL) with riboflavin and UVA light is a therapeutic procedure to restore the mechanical stability of corneal tissue. The treatment method applies to pathological tissue changes, such as keratoconus. It induces the photochemical formation of new collagen cross-links. Although therapeutic effects are indisputable, the exact molecular process of CXL and how cross-links are formed is still unclear. In this work, Fouriertransform infrared (FT-IR) spectroscopy is used to investigate the cross-linking process. For that purpose, in-situ experiments with porcine corneas are carried out using attenuated total reflection (ATR) spectroscopy. Furthermore, IR micro-spectroscopic imaging in transmission mode is used to investigate thin tissue sections of the cornea and initial approaches for the distinction of cross-linked and untreated tissue by IR microspectroscopic imaging were performed. Multivariate methods are applied to access changes that occur as a result of CXL. It is shown that spectral changes after cross-linking are caused predominantly by an increase of methyl- and methylene groups as well as primary and secondary amines. In addition, a decrease of carbonyl groups could be observed.

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The tensile strength of the intervertebral disc (IVD) is mainly maintained by collagen cross‐links. Loss of collagen cross‐linking combined with other age‐related degenerative processes contributes to tissue weakening, biomechanical failure, disc herniation and pain. Exogenous collagen cross‐linking has been identified as an effective therapeutic approach for restoring IVD tensile strength. The current state‐of‐the‐art method to assess the extent of collagen cross‐linking in tissues requires destructive procedures and high‐performance liquid chromatography. In this study, we investigated the utility of infrared attenuated total reflection (IR‐ATR) spectroscopy as a nondestructive analytical strategy to rapidly evaluate the extent of UV‐light‐activated riboflavin (B2)‐induced collagen cross‐linking in bovine IVD samples. Thirty‐five fresh bovine‐tail IVD samples were equally divided into five treatment groups: (a) untreated, (b) cell culture medium Dulbecco's Modified Eagle's Medium only, (c) B2 only, (d) UV‐light only and (e) UV‐light‐B2. A total of 674 measurements have been acquired, and were analyzed via partial least squares discriminant analysis. This classification scheme unambiguously identified individual classes with a sensitivity >91% and specificity >92%. The obtained results demonstrate that IR‐ATR spectroscopy reliably differentiates between different treatment categories, and promises an excellent tool for potential in vivo, nondestructive and real‐time assessment of exogenous IVD cross‐linking. [ABSTRACT FROM AUTHOR]

Herein, finite‐element analysis is used to optimize the performance of mid‐infrared (MIR) (7.7–13.7 μm) waveguides by selecting optimal waveguide and substrate materials, waveguide size, and boundary field. The results show that a diamond waveguide has a substantially higher sensitivity than Si‐ or Ge‐based waveguides owing to its higher boundary evanescent field at the same depth. Furthermore, it is found that AlN substrates have better optical stabilities than SiO2 and Si3N4 substrates, because AlN substrates do not have apparent absorption characteristics in the MIR range (7.7–13.7 μm). Geometry of diamond waveguide on AlN substrate is optimized, and a section length of 45 μm is chosen for optimal signal transmission quality. The calculations of the infrared attenuated total reflection (ATR) of the diamond waveguide applied to water, alcohol, and diisopropyl methyl phosphate are highly consistent with the actual infrared absorption spectrum. This proves the feasibility of applying AlN/diamond waveguides in MIR ATR detection, which is of great significance for the preparation of high‐sensitivity MIR detectors. [ABSTRACT FROM AUTHOR]

Diazoquinone–novolac photoresist FP9120 films of 1.0–2.5 μm in thickness with boron ions, implanted at an incident ion energy of 60 keV and a fluence of 5 × 1014–1 × 1016 cm−2, have been studied using attenuated total reflection (ATR) FTIR spectroscopy. It has been shown that ion implantation leads to the appearance in the layer beyond the range of ions of intense ATR bands with maxima at 2151 and 2115 cm−1 due to stretching vibrations of C=C=O cumulative double bonds formed as a result of denitrogenation of o‑naphthoquinone diazide. During implantation, a redistribution of intensities was observed between the maxima of the ATR bands due to the terminal methyl groups and methylene groups in favor of the latter. This may indicate radiation crosslinking of novolac resin molecules, involving radicals with the unpaired electron localized at the terminal methyl groups. [ABSTRACT FROM AUTHOR]