Infrared Reflectance Spectroscopy Research Articles

Oxygen Electroreduction on the Anthraquinone-Modified Thin-Film Carbon–Polymer Composite in Alkaline Solution

Technical carbon CH210 was processed by chemical reduction of the diazo derivative of anthraquinone for surface modification. The presence of anthraquinone groups on the carbon surface was confirmed by attenuated total internal reflection (ATR) IR spectroscopy. Carbon with the anthraquinone-modified surface was deposited on a glassy carbon support using a polymer binder. The behavior of the thus obtained catalyst in oxygen electroreduction in an alkaline medium was studied by the rotating disk electrode method. The kinetic characteristics of the reaction were determined: half-wave potential, limiting current, number of electrons, Tafel slope, exchange current, and charge transfer coefficient. Hydrogen peroxide is formed on the surface of the carbon–polymer composite at higher positive potentials than on technical carbon and glassy carbon electrodes. Therefore, the proposed material can be used as an effective electrocatalyst for this reaction.

Development of a Method for Identifying Wood Species in Archaeological Materials by IR Spectroscopy

We investigated 53 coniferous wood samples and 77 deciduous wood samples of trees in the central Russia by single-reflection attenuated total reflection IR spectroscopy. The characteristic absorption bands in the IR spectra of the samples are described, and the regions of absorption bands characteristic of coniferous and deciduous wood are identified. Characteristic differences in the spectra of coniferous and deciduous wood species suitable for their identification are found. Wood species of three archaeological materials were identified using these characteristic differences.

Dynamics of Lignin Destruction in Pine Wood under the Action of Ozone

The destruction of lignin in pinewood during ozonization is studied via diffuse reflection IR spectroscopy (DRIFT) and Raman spectroscopy. The DRIFT spectra are deconvoluted into Lorentz components. Samples of dioxanlignin obtained from wood are analyzed by means of UV spectroscopy (second derivatives). Based on the DRIFT, Raman, and UV spectra, specific rates of ozone (Qr) consumption corresponding to the oxidation of different structures on the wood surface are determined. In the range of Qr ≤ 1.5 mmol/g, the predominant process is the breakdown of aromatic rings. In the range of 1.5–3.0 mmol/g, hydroxyaromatic compounds formed at the first stage of ozonization are oxidized. At Qr higher than 2.0 mmol/g, aliphatic structures of lignin are also oxidized by ozone, along with carbonyl and carboxylic oxidation products occurring on the surface. These lignin oxidation products block to some extent the accessibility of lignin for ozone.

Mesoporous Co3O4 catalysts for VOC elimination: Oxidation of 2-propanol

Mesoporous cobalt oxides were prepared by an inverse micelle method and calcined at different temperatures. These materials exhibited superior activity for oxidation of 2-propanol as the model substrate for VOC elimination. Highest active Co3O4-350 material showed a maximum turnover frequency of 25.8 h−1 at 160 °C at a weight hourly space velocity of 60 L g-1 h−1. The apparent activation energies of mesoporous cobalt oxides ranged from 69.7 kJ/mol to 115.6 kJ/mol. In situ Diffuse Reflectance Infrared spectroscopy (DRIFTS) revealed that the reaction involves formation of carbonyl and carbonate species on the surface of the catalyst before complete oxidation to CO2 and H2O. The activities of the materials were correlated to better low temperature reducibility, large pore volumes, higher Co3+/ Co2+ ratios, and higher number of surface-active oxygen species.

Estimation of Secondary Soil Properties by Fusion of Laboratory and On-Line Measured Vis–NIR Spectra

Visible and near infrared (vis–NIR) diffuse reflectance spectroscopy has made invaluable contributions to the accurate estimation of soil properties having direct and indirect spectral responses in NIR spectroscopy with measurements made in laboratory, in situ or using on-line (while the sensor is moving) platforms. Measurement accuracies vary with measurement type, for example, accuracy is higher for laboratory than on-line modes. On-line measurement accuracy deteriorates further for secondary (having indirect spectral response) soil properties. Therefore, the aim of this study is to improve on-line measurement accuracy of secondary properties by fusion of laboratory and on-line scanned spectra. Six arable fields were scanned using an on-line sensing platform coupled with a vis–NIR spectrophotometer (CompactSpec by Tec5 Technology for spectroscopy, Germany), with a spectral range of 305–1700 nm. A total of 138 soil samples were collected and used to develop five calibration models: (i) standard, using 100 laboratory scanned samples; (ii) hybrid-1, using 75 laboratory and 25 on-line samples; (iii) hybrid-2, using 50 laboratory and 50 on-line samples; (iv) hybrid-3, using 25 laboratory and 75 on-line samples, and (v) real-time using 100 on-line samples. Partial least squares regression (PLSR) models were developed for soil pH, available potassium (K), magnesium (Mg), calcium (Ca), and sodium (Na) and quality of models were validated using an independent prediction dataset (38 samples). Validation results showed that the standard models with laboratory scanned spectra provided poor to moderate accuracy for on-line prediction, and the hybrid-3 and real-time models provided the best prediction results, although hybrid-2 model with 50% on-line spectra provided equally good results for all properties except for pH and Na. These results suggest that either the real-time model with exclusively on-line spectra or the hybrid model with fusion up to 50% (except for pH and Na) and 75% on-line scanned spectra allows significant improvement of on-line prediction accuracy for secondary soil properties using vis–NIR spectroscopy.

Syntheses, structures and properties of copper(II) and cobalt(II) complexes with 5(3)-amino-2-chloro-3(5)-methylpyridine isomer cations

New coordination compounds of copper(II) and cobalt(II) with 5-amino-2-chloro-3-methylpyridine (L1) and 3-amino-2-chloro-5-methylpyridine (L2) of the following composition: (HL1)2[CuCl4] (1), (HL1)2[CoCl4]·HCl·H2O (2), (HL2)2[CuCl4]·H2O (3), (HL2)2[CuCl4]·2H2O (4) and (HL2)2[CoCl4] (5), have been synthesized. In an acetone environment, L1 may undergo a Schiff condensation reaction and the product of its complexation [CuL1*Cl3] (6) was also obtained. The compounds have been investigated by single-crystal X-ray diffraction, simultaneous TG–DSC analysis, IR and diffuse reflectance spectroscopy, and temperature-dependent magnetic susceptibility measurements. Exchange interactions between the unpaired electrons of the metal ions have a different character depending on the composition of the complexes. For the Cu(II) compounds: 1, 2D-ferromagnetic layer, J = 13.53(15) K; 3, strong-rung ladder, Jrung = −7.26(1) K, Jrail = −1.87(2) K; 4, uniform chain, J = −4.1(1) K. The magnetic properties of the Co(II) compounds are dominated by single-ion anisotropy with D = −22(1) K (2) and −8.7(2) K (5). The copper(II) complexes show thermochromic behavior.

Influence of Ti4+ substitution for Ta5+ on the crystal structure, Raman spectra, and microwave dielectric properties of Ba3Ta4-4xTi4+5xO21 ceramics

This paper systematically investigated the influence of Ti4+ substitution for Ta5+ on the phase composition and microwave dielectric properties of Ba3Ta4-4xTi4+5xO21 (x = 0.1, 0.2, and 0.3) ceramics with hexagonal tungsten bronze-like structures. X-ray diffraction and Rietveld refinement results indicated that single-phase Ba3Ta4Ti4O21 could be obtained only with the x values of 0.1 and 0.2, and a secondary phase was detected at an x value of 0.3. The valence state of Ba3Ta4-4xTi4+5xO21 (x = 0.2) ceramics was analyzed through X-ray photoelectron spectroscopy. Increasing Ti4+/Ta5+ ratios could reduce sintering temperature and improve the microwave dielectric properties of Ba3Ta4-4xTi4+5xO21 solid solutions. However, the dielectric properties, particularly the quality factor, of Ba3Ta4-4xTi4+5xO21 ceramics deteriorated severely as a result of oxygen vacancy defects caused by the transition of the valence state from Ti4+ to Ti3+ when x = 0.2 and the coexistence of the secondary phase when x = 0.3. Infrared reflectivity spectroscopy was performed to explore the intrinsic dielectric properties of Ba3Ta4-4xTi4+5xO21 (x = 0.1) ceramics. The measured and extrapolated microwave dielectric properties of Ba3Ta4-4xTi4+5xO21 (x = 0.1) ceramics sintered at 1240 °C for 6 h were εr ~ 46.5, Q × f = 13,900 GHz, τf ~ +49.4 ppm/°C, and εr ~ 44, Q × f = 34,850 GHz.

Visible/near infrared spectroscopy method applied research in wetland soil nutrients rapid test

Visible/near infrared spectrum method has the advantages of fast and green, there is much better technical superiority in soil nutrients on-site detection. Studying on wetland soil samples from 4 districts of Qingdao with higher heterogeneity, according to its total nitrogen (TN), available nitrogen (AN), total phosphorus (TP), available phosphorus (AP), total potassium (TK), slowly available potassium (SK) and available potassium (FK) content and visible/near infrared reflectance spectroscopy, adopted SPA and PLSR to choose characteristic wavelength and build mode. Modeling results and experimental data indicated that this method to the content of TN, AN, TP, AP and FK in wetland, can be predicted accurately, it also can be predicted the content of TK and SK roughly.

Vis/NIR reflectance spectroscopy for hybrid rice variety identification and chlorophyll content evaluation for different nitrogen fertilizer levels.

Nitrogen is one of the most important nutrient indicators for the growth of crops, and is closely related to the chlorophyll content of leaves and thus influences the photosynthetic ability of the crops. In this study, five hybrid rice varieties were cultivated during one entire growing period in one experimental field supplied with six nitrogen fertilizer levels. Visible and near infrared (vis/NIR) reflectance spectroscopy combined with multivariate analysis was used to identify hybrid rice varieties and nitrogen fertilizer levels, as well as to detect chlorophyll content associated with nitrogen levels. The support vector machine (SVM) algorithm was applied to identify five varieties of hybrid rice and six levels of nitrogen fertilizer. The results demonstrated that different varieties of hybrid rice for each nitrogen level can be well distinguished except for the highest nitrogen level, and no nitrogen level for each rice variety can be completely identified from the other five nitrogen levels. Further, 12 spectral indices combined with partial least square (PLS) analysis were applied for estimating chlorophyll content of rice leaves from plants subjected to different nitrogen levels, and a root mean square error of cross-validation (RMSECV) of 0.506, a coefficient of determination (R2) of 97.8% and a ratio of performance to deviation (RPD) of 4.6 for all rice varieties indicated this as a preferable procedure. This study demonstrates that Vis/NIR spectroscopy can have a great potential for identification of rice varieties and evaluation of nitrogen fertilizer levels.

Chemically-Modified Activated Carbon with L-Arginine for Selective Solid Phase Extraction and Preconcentration of Metal Ions

In this study, a new sorbent of chemically-modified activated carbon with L-arginine (AC-Arg) has been produced as solid-phase extraction, to trace Zn(II) and Cd(II) ions in real samples, including soil and water samples, by Flame Atomic Absorption Spectrometry (FAAS). Once the surface coverage value is determined, the surface modification has been investigated and assessed, while having employed both elemental analysis as well as Attenuated Total Reflection InfraRed (ATR-IR) spectroscopy. The separation/preconcentration factors of the analyte, including the effect of pH, shaking time, sample volume, elution condition, and interfering ions have been studied. Following the International Union of Pure and Applied Chemistry (IUPAC) recommendations, the detection limits (3σ) of these methods are 2.4 and 1.6 ng/mL, using AC-Arg for Zn(II) and Cd(II) respectively. The relative standard deviation (RSD) under optimum conditions is less than 1% (n=6).

Highly Selective Anaerobic Oxidation of Alcohols Over Fe‐doped SrTiO3 Under Visible Light

AbstractPhotocatalytic oxidation of alcohols with high selectivity is a promising approach for the synthesis of organic compounds under mild conditions and for solar energy conversion. In this work, we report on the highly selective anaerobic photooxidation of alcohols to carbonyl compounds with coupled H2 production over Pt‐loaded Fe‐doped SrTiO3 under visible light. Representatively, an optimized apparent quantum efficiency of 13.2 % at 420 nm was obtained for benzyl alcohol oxidation. X‐ray absorption fine structure and in situ diffuse reflectance IR spectroscopy revealed that the surface oxygen vacancies and the fine‐tuned valence band edge position induced by Fe doping not only contributed to the activation of α‐C−H bonds in alcohols, but also avoided the over‐oxidation of the obtained carbonyl compounds.

Determination of the bruise degree for cherry using Vis-NIR reflection spectroscopy coupled with multivariate analysis.

Determination and classification of the bruise degree for cherry can improve consumer satisfaction with cherry quality and enhance the industry’s competiveness and profitability. In this study, visible and near infrared (Vis-NIR) reflection spectroscopy was used for identifying bruise degree of cherry in 350–2500 nm. Sampling spectral data were extracted from normal, slight and severe bruise samples. Principal component analysis (PCA) was implemented to determine the first few principal components (PCs) for cluster analysis among samples. Optimal wavelengths were selected by loadings of PCs from PCA and successive projection algorithm (SPA) method, respectively. Afterwards, these optimal wavelengths were empolyed to establish the classification models as inputs of least square-support vector machine (LS-SVM). Better performance for qualitative discrimination of the bruise degree for cherry was emerged in LS-SVM model based on five optimal wavelengths (603, 633, 679, 1083, and 1803 nm) selected directly by SPA, which showed acceptable results with the classification accuracy of 93.3%. Confusion matrix illustrated misclassification generally occurred in normal and slight bruise samples. Furthermore, the latent relation between spectral property of cherries in varying bruise degree and its firmness and soluble solids content (SSC) was analyzed. The result showed both colour, firmness and SSC were consistent with the Vis-NIR reflectance of cherries. Overall, this study revealed that Vis-NIR reflection spectroscopy integrated with multivariate analysis can be used as a rapid, intact method to determine the bruise degree of cherry, laying a foundation for cherry sorting and postharvest quality control.

In-Situ Infrared Spectroscopy Applied to the Study of the Electrocatalytic Reduction of CO2 : Theory, Practice and Challenges.

The field of electrochemical CO2 conversion is undergoing significant growth in terms of the number of publications and worldwide research groups involved. Despite improvements of the catalytic performance, the complex reaction mechanisms and solution chemistry of CO2 have resulted in a considerable amount of discrepancies between theoretical and experimental studies. A clear identification of the reaction mechanism and the catalytic sites are of key importance in order to allow for a qualitative breakthrough and, from an experimental perspective, calls for the use of in-situ or operando spectroscopic techniques. In-situ infrared spectroscopy can provide information on the nature of intermediate species and products in real time and, in some cases, with relatively high time resolution. In this contribution, we review key theoretical aspects of infrared reflection spectroscopy, followed by considerations of practical implementation. Finally, recent applications to the electrocatalytic reduction of CO2 are reviewed, including challenges associated with the detection of reaction intermediates.

Gravimetric and Spectrophotometric Determination of Surface Wax Content in Maize Kernels

There are several methods available to determine wax content in maize kernel. These methods are based on gravimetric, spectrophotometric, and chromatographic analyses. This study aims to determine the surface wax content on maize kernel with different reference methods and develop NIR (Near Infrared Reflectance Spectroscopy) calibration models based on those reference methods. In this study, samples from 250 different maize genotypes were used. Surface wax content in the samples was determined by gravimetric and UV-Spectrophotometric methods. The results of each reference method were used to develop NIR prediction models for surface wax content in kernel samples. Our results suggest that there is a medium-level correlation (r=0.708) between the data obtained from spectrophotometric and gravimetric methods. Also, significant differences were observed between the wax content obtained from reference methods. It has been found that the NIR calibration model (RMSE =4.381, R2 =0.143, r =0,378, RPD =1.08) based on the gravimetric method had lower estimation power than the NIR calibration model (RMSEC =7.257, R2 =0.221, r =0.471, RPD =1.34) based on the UV spectroscopic method. Keywords: Near Infrared Spectroscopy, Biochemical test, Zea mays, Regression DOI: 10.7176/JSTR/5-9-11

Reconstitution de l’histoire de la couverture végétale des chernozems d’Europe par la spectroscopie proche infrarouge qualitative

Chernozems are considered to be typical soils of continental steppe environments. Nonetheless, they exist in many areas in Central Europe, where the climate is convenient for the growth of trees and forest vegetation. Otherwise, these areas of Central Europe have been under intensive human influence since the Neolithic period. The natural conditions of the distribution of chernozems in Central Europe cannot be identified without taking into account relevant palaeoenvironmental data. Qualitative near infrared reflectance spectroscopy (NIRS) was proven to be an innovative method to discover the vegetational origin of soil organic matter (SOM). In our study, we developed a special NIRS reference library for chernozems and soils on loess that is based on two reference groups: soils under grassland and soils under woodland. In order to explore their palaeoenvironmental history in Central Europe, we applied the reference library on a set of 23 sites of European chernozems. We concluded that the majority of the examined chernozems have a grassland past, but some of them had also existed under woodland. The chernozems, which are currently under woodland, have a grassland past. Landscape management is a crucial factor for the pedogenesis of chernozems in Central Europe since the Neolithic. Therefore, it is inappropriate to subscribe the development of these soils just to one scenario or to consider the presence of chernozems as an undoubtable proxy for continuous grassland in the Holocene.

Structural Nanocomposite Fabrication from Self-Assembled Choline Chloride Modified Kaolinite into Poly(Methylmethacrylate)

Composite materials produced from indigenous nanoscale particles and synthetic polymers have created demand in the field of nanoscience and technology. Layered silicates are potential candidates for reinforcing the properties of composites. Here, we report the fabrication of nanocomposites using poly(methylmethacrylate) (PMMA) as the matrix and the Bijoypur clay of Bangladesh known as kaolinite (200–250 nm) as the filler via solution casting. Kaolinite was first modified using choline chloride to prepare core-shell particles through a precipitation technique and was used for self-assembled nanocomposite films preparation. A series of nanocomposites films using 0, 1, 3, 5 and 10% (w/w) modified kaolinite was prepared. The neat PMMA and nanocomposite films were characterized by attenuated total reflection infra-red (ATR-IR) spectroscopy and X-ray diffraction (XRD) techniques. The mechanical properties, thermal stability, and morphology of the films were investigated using a universal testing machine (UTM), a thermal gravimetric analyzer (TGA), and a scanning electron microscope (SEM). The nanocomposite films exhibited better mechanical properties and thermal stability than neat PMMA film. Development of such structural nanocomposite materials using naturally occurring nanoscale particles would play a crucial role in the field of materials science for packaging applications and separation technology.

Detection of adulterated beeswax by the method of infrared reflection spectroscopy

Detection of adulterated beeswax by the method of infrared reflection spectroscopy

Zr- and La-containing Catalysts in Synthesis of Methanol and Dimethyl Ether

Zirconium oxide samples synthesized and modified with Al, Si, W oxides were studied as dehydrating components of bifunctional catalysts for synthesis of dimethyl ether. ZrO2 modified with Al and Si oxides is inactive in the dehydration of methanol, but its dehydrating activity becomes comparable with the activity of γ-Al2O3 upon introduction of WO3. According to the data on methanol adsorption at 46°C, the adsorption capacity of ZrO2 modified with SiO2 is comparable with the capacity of γ-Al2O3, and that of ZrO2 modified with WO3 is four times lower. The difference in the catalytic and adsorption behavior of the samples is accounted for by the data of in situ high-temperature diffuse reflection IR spectroscopy. A high content of weak Bronsted acid centers is observed on the ZrO2 surface, with the interaction of these with methanol resulting in the methoxylation of the catalyst surface. When W oxide is deposited onto zirconium oxide, the surface has strong Bronsted centers involved in the reaction of methanol dehydration. A coprecipitation from solution of nitrate salts of Cu, Zn, La with Na carbonate, followed by the procedures of filtration, washing, and thermal treatment, yielded a catalyst for synthesis of methanol, the activity of which is close to that of the industrial catalyst.

121 Non-invasive monitoring of hot-iron brands on growing cattle

Abstract Hot-iron branding is a traditional form of permanent cattle identification that produces a scar. There is a need for science-based determination of cattle brand age through non-invasive monitoring of the healing process. Near infrared reflectance spectroscopy (NIRS) has been used by medical forensic scientists to obtain such information. Healing of cutaneous injury involves inflammatory (1 to 3 d), proliferative (4 to 21 d), and remodeling (22 to 365 d) phases. Collagen changes as burn scars mature, i.e. there is an increase in the Type I/ Type III collagen ratio compared to normal skin. The altered ratio is evident in a transformation of collagen from a basketweave arrangement to small parallel bundles. During the remodeling phase, due largely to the Type I/III collagen ratio, scar tissue becomes visibly different than un-injured skin. Previous research has examined the differences in hot-iron brands applied to nursing (~30 d old) Bos taurus cross calves at 0, 33, and 153 d post-branding. Our objective was to continue this research by obtaining near infrared spectra (11001700nm) on hot-iron brands applied to 15 weaned (~ 270 d old; 238 ± 7kg) Bos taurus cross steers at 21, 32, and 51 d post-branding. Spectra were obtained on branded (n = 3) and unbranded (n = 3) skin tissue from each animal, each date. Hair was clipped to < 5mm on unbranded skin. Spectra were analyzed as log 1/reflectance with 1st derivative and scatter correction applied. Linear discriminant analysis and regression procedures were applied to distinguish between brand treatment and date post-branding. Spectra from branded and unbranded skin were correctly (P < 0.05) identified at ~95%. Brand age was predicted successfully (P < 0.05) but not accurately enough for forensic application (RSQ = 0.50; RMSE = 9.75 d). The NIRS technique can discriminate differences in the age of cattle brand scars but numerical prediction requires further investigation.

Near Infrared Reflectance spectroscopy to analyse texture related characteristics of sous vide pork loin.

This study aims to evaluate the ability of the Near Infrared Reflectance spectroscopy (NIRs) technique to analyse texture-related characteristics of sous-vide pork loins at different times of cooking. For that, pork loins were sous-vide at 70 °C for 1, 2, 4, 6 and 8 h. Cooked samples were analysed by means of NIRs, instrumental (cooking loss, pH, moisture, hydrolysed collagen and texture profile analysis) and sensory analysis. Classification and predictive techniques of data mining were applied on the obtained data. Sous-vide loins were correctly classified as a function of time of cooking and their texture-related characteristics were predicted accurately, achieving correlation coefficients (R) higher than 0.5 and Mean Absolute Scaled Errors lower than 1 for most parameters. Thus, it is demonstrated the capability of NIRs to analyse most texture-related parameters of warm loin samples, and it may be recommended as a rapid and automatic techniques to stablish optimal cooking conditions of food.