Near-infrared Transmittance Research Articles

Effects of isomerism on near infrared properties of perylene bisimide derivatives

In this study, five different perylene bisimide derivatives are synthesized, four of which are structural isomers. The pigments are used to prepare corresponding paints and their ultraviolet–visible–near infrared (NIR) reflectance is investigated on two optically different substrates, namely high absorptive and high reflective substrates. These pigments are classified according to their NIR properties. They show substantial differences in NIR reflectance, transmittance, and absorbance despite their structural similarities. This indicates that the NIR properties of perylene bisimide derivatives are dependent on the nature of N-substituent and electronic environment of the molecule. This study shows that the existence of bonds with high-frequency fundamental vibrations and their counts which were introduced as affecting parameters on the NIR properties of the perylene pigments is not the main affecting factor and we should seek it elsewhere such as the crystal structure and intermolecular interactions of the pigments.

Identification of Brake Fluid Brands, New and Used Brake Fluid with Discriminant Analysis Based on Near-Infrared Transmittance Spectroscopy.

Near-infrared transmittance spectroscopy was used to identify brake fluid brands, new and used brake fluid of each brand. The transmittance spectra of the new and used samples of 4 different brands of brake fluid, including BMW, Toyota, Volvo and Castrol were collected. PCA was conducted to the spectral data of the new samples of the four brake fluid and the spectral data of the new and used samples of each brand. The PCA scores scatter plot indicated that there were differences among the four brands of brake fluid, and there were also differences between new and used samples of each brand. Optimal wavelengths were selected for identifying different brands and new and used samples of each brand by loadings of PCA. Classification models were built using the optimal wavelength, including Partial least squares-discriminant analysis (PLS-DA), Linear discriminant analysis (LDA), Soft independent modeling of class analogy (SIMCA), k-nearest neighbor algorithm (KNN), Random forest (RF), Back propagation neural network (BPNN), Radial basis function neural network (RBFNN), Extreme learning machine (ELM), Support vector machine (SVM), Least-squares support vector machine (LS-SVM). All classification models obtained good performances, the classification accuracy of the calibration set and the prediction set are 100% for most models. Compared with other three brands, new and used samples of Castrol showed slighter difference, and KNN and LS-SVM models performed worse with classification accuracy under 100% in the calibration set. The overall results indicated that near-infrared transmittance combined with optimal wavenumber selection and classification methods could be used to identify brake fluid brands, new and used brake fluids, the results of this study could provide theoretical support for developing online and portable devices.

Fabrication of Cs0.32WO3/SiO2 aerogel multilayer composite coating for thermal insulation applications

A novel Cs0.32WO3/SiO2 aerogel multilayer composite coating has been fabricated on glass substrate using the colloidal dispersion of Cs0.32WO3 and SiO2 aerogel nanoparticles, respectively. The effects of SiO2 aerogel layer thickness on the visible and near-infrared light transmittance of Cs0.32WO3/SiO2 composite coating have been investigated. The results indicate that the composite coating can achieve maximum visible light transmission when the thickness of SiO2 aerogels layer is 138µm. When the aerogel layer thickness exceeds 138µm, the light transmittance has a decreasing trend and near infrared shielding rate tends to increase further. It is expected that the Cs0.32WO3/SiO2 aerogel multilayer composite coatings with appropriate aerogel layer thickness would not only have higher visible light transmittance, but also have excellent near-infrared shielding and thermal insulation performance.

Assessment and prediction of tablet properties using transmission and backscattering Raman spectroscopy and transmission NIR spectroscopy

This study investigated whether Raman and Near Infrared (NIR) spectroscopy could predict tablet properties. Granules were produced on a continuous line by varying granulation parameters. Tableting process parameters were adjusted to obtain uniform tablet weight and thickness. Spectra were collected offline and tablet properties determined with traditional analyzing methods. Partial Least Squares (PLS) regression was used to correlate spectral information to tablet properties, but predictive models couldn't be established. Principal component analysis (PCA) was effectively used to distinguish theophylline concentrations and hydration levels and multiple linear regression (MLR) analysis allowed insight on how granulation parameters affect granule and tablet properties.

Void fraction measurement using NIR technology for horizontal wet-gas annular flow

It is difficult to measure the void fraction of wet-gas annular flow due to the low water holdup. The near infrared (NIR) spectrum has characteristic absorption band for water, which can increase the sensibility to water in the void fraction measurement of wet-gas annular flow. This paper presents a void fraction measurement method based on NIR spectrum. A non-invasive sensor was designed in this paper. According to characteristic O–H absorption band of H2O, 970nm was selected as the emission wavelength of NIR light source. Considering absorption of liquid film, scattering of entrained droplets and interface reflection of two-phase, a void fraction model base NIR transmittance was constructed and further simplified. Utilizing the simplified model and designed sensor, void fraction measurements had been obtained for 48 horizontal wet-gas annular flow conditions in the pipeline pressure of 0.4MPa and 0.5MPa. Laboratory results indicate that the relative deviations of the measurement model range from −5.53% to 7.34%, but the 93.75% of relative deviations are within ±5%.

Near infrared spectroscopic transmittance measurements for pharmaceutical powder mixtures

This study describes the development of near infrared (NIR) calibration models using transmittance measurements in powder samples and compares the results obtained with those of tablet transmittance and diffuse reflectance of powders. Transmission near infrared spectroscopy is a method widely used for the analysis of tablets in the evaluation of drug concentration due to the larger sample volume analyzed, but not commonly used for the analysis of powder samples. Diffuse reflection near infrared spectroscopy is a method used in both powder and tablets for the evaluation of quality attributes. In this initial study NIR transmittance measurements were obtained using an off-line spectrometer equipped with a high intensity light source. Spectra were obtained with three different resolutions for the analysis of powder and tablet samples of 7.50–22.50% (w/w) acetaminophen. The Partial Least Squares (PLS) calibration models developed include pretreatments such as Standard Normal Variate (SNV) and first derivative in the region from 9500–7500cm−1. Transmittance in powder presented low Root Mean Square Error of Prediction (RMSEP) values that varied from 0.23–1.15% (w/w) APAP with resolution of 64 and 16cm−1. The lowest RMSEP values (0.23–0.39% (w/w) APAP) were obtained using a resolution of 64cm−1. The RMSEP values for powder transmittance measurements were 2.4–5.6 times lower than the diffuse reflectance measurements of the powder mixtures.

Near-infrared wavelength-dependent nonlinear transmittance tailoring in glass ceramics containing Er3+:LaF3nanocrystals

Tailoring optical nonlinear transmittance relying on excitation at various NIR wavelengths in LaF3:Er3+nanocrystals embedded in germanate oxyfluoride glass ceramics.

Tunable Metal-Insulator Properties of Vanadium Oxide Thin Films Fabricated by Rapid Thermal Annealing

Vanadium oxide (VOx) thin films were fabricated by sputtering vanadium thin films on c-sapphire substrate followed by rapid thermal annealing in pure oxygen atmosphere. The surface morphology, crystal structure, electrical characteristics and near-infrared transmittance of the VOx films were studied by atomic force microscope (AFM), X-ray diffraction (XRD), four-point probe method and FT-IR/NIR Spectrometer, respectively. The insulator-metal phase transition temperature could be easily tuned from 57 to 49°C during heating and from 48 to 42°C during cooling by controlling the annealing time of rapid thermal annealing. This modulation effect of phase transition temperature is explained by carrier concentration originating from the different annealing times. The films with higher carrier concentration and smaller VO2 grain size tend to have lowered phase transition temperature. Besides, the widths of the hysteresis loops can also be regulated by controlling the annealing time. In addition, we find that films with coarser crystal sizes generally have a narrower hysteresis width. These results confirmed experimentally that carrier concentration, grain size and morphology of VOx films have significant effects on the properties of the metal-insulator transition; and rapid thermal process is a simple and effective way to tune phase transition properties of vanadium oxide thin films.

Assessment of the light extinction spectroscopy technique for submicron particle characterization

The present paper is dedicated to the assessment of the Light Extinction Spectroscopy (LES) technique for the characterization of submicron particles. This technique allows the measurement of the size distribution of a particle cloud starting from its Ultraviolet Near-Infrared light transmittance spectrum and is applicable in the size range going from few nanometers up to dozens of microns. The main goal of the present work is to validate the technique experimentally, using as reference both an established commercially available instrument and calibrated spherical particles.In particular, the experimental validation of the LES technique is presented for potassium chloride (KCl) and polystyrene (PS) submicron particles. In the case of KCl particles, the validation is obtained using simultaneously a Scanning Mobility Particle Sizer (SMPS), while for PS particles calibrated spheres are used. It is demonstrated that both for monodisperse and polydisperse particle size distributions, the LES technique is in a satisfactory quantitative agreement in terms of the particle size distribution function.

Two-dimensional hetero-spectral mid-infrared and near-infrared correlation spectroscopy for discrimination adulterated milk

A new approach for discriminant analysis of adulterated milk is proposed based on two-dimensional (2D) hetero-spectral near-infrared (NIR) and mid-infrared (IR) correlation spectroscopy along with multi-way partial least squares discriminant analysis (NPLS-DA). NIR transmittance spectra and IR attenuated total reflection spectra of pure milk and adulterated milk with level of melamine varying from 0.03 to 3g·L−1 were collected at room temperature. The synchronous 2D hetero-spectral IR/NIR correlation spectra of all samples were calculated to build a discriminant model to classify adulterated milk and pure milk. Also, the NPLS-DA models were built based on synchronous 2D homo-spectral NIR/NIR and IR/IR correlation spectra, respectively. Comparison results showed that the NPLS-DA model could provide better results using 2D hetero-spectral IR/NIR correlation spectra than using 2D homo-spectral NIR/NIR and 2D IR/IR correlation spectra.

Using Vis/NIR Diffuse Transmittance Spectroscopy and Multivariate Analysis to Predicate Soluble Solids Content of Apple

The objectives of this research were to compare the effect of different fruit orientations on the quality of acquired spectra and to provide a suitable calibration model for further online determination of soluble solids content (SSC) of “Fuji” apples using visible and near-infrared (Vis/NIR) diffuse transmittance. The diffuse transmittance spectra between 650 and 910 nm were collected with the designed spectrum measurement system in two fruit orientations: stem-calyx axis horizontal (T1) and stem-calyx axis vertical (T2). Area change rate (ACR) was used to evaluate the stability of spectra collected in two fruit orientations. Results showed that the fruit orientation T1 was better for our designed spectrum measurement system. Then, the performance of partial least squares (PLS) models based on spectral data after the pretreatment of several preprocessing methods was analyzed and compared. Finally, the modified competitive adaptive reweighted sampling (MCARS), successive projection algorithm (SPA), and their combination were investigated to select the effective variables for the determination of SSC. It concluded that the MCARS-SPA-PLS model based on the spectra after preprocessing of Savitzky-Golay (SG) smoothing achieved better results for SSC prediction. The correlation coefficients between measured and predicted SSC were 0.962 and 0.946, and the root mean square errors were 0.510 and 0.527°Brix for calibration and prediction set, respectively. Moreover, the physicochemical properties of 27 variables selected by MCARS-SPA were discussed to obtain a better interpretation of the calibration model. The overall results indicated that the designed diffuse transmittance spectrum measurement system together with the PLS calibration model with 27 effective variables selected by MCARS-SPA method had a potential application for online SSC detection of apple.

Using near infrared transmittance to generate sorted fractions of Fusarium-infected wheat and the impact on broiler performance

The objective of this study was to investigate the effects of naturally contaminated Fusarium wheat containing deoxynivalenol (DON) on growth and performance of broiler chickens from 0 to 35 d. The BoMill TriQ individual kernel sorting technology uses near infrared transmittance (NIT) spectra to separate Fusarium-damaged kernels (FDK) from healthy kernels based on individual kernel CP. Three Fusarium-contaminated wheat sources were individually sorted into 3 test fractions: outlier (10% of the source), high mycotoxin (20% of the source), and low mycotoxin (70% of the source). These fractions were reconstituted into 4 ratios—M0, M20, M40, and M60—relating to the proportion of the high mycotoxin fraction in the reconstituted diets. These 12 reconstituted wheat sources with varying levels of DON were incorporated at ∼70% (starter) or ∼75% (grower/finisher) into diets. The fractions of wheat used had FDK ranging from 0.1 to 25.8% and DON from 0.0 to 14.3 ppm. A total of 480 newly hatched Ross 308 male broilers were randomly divided into 96 cages. Each test diet was assigned to 8 replicates with 5 birds per replicate cage. At 21 d, 180 birds were transferred to 36 cages, allowing 3 replicates of 5 birds per diet until 35 d. A factorial arrangement analysis compared the 3 wheat sources and 4 ratios produced from each sorted wheat. Growth and performance were evaluated as BW (g), feed intake (FI; g/bird/day), feed conversion ratio (FCR; g:g), AME (kcal ME/kg diet), nitrogen retention (NR; %), and mortality (%) for 0 to 21 d and 21 to 35 d. Results indicate no significant difference in BW, FI, and FCR (P > 0.05). Significant differences were seen in AME and NR (P < 0.01). This study demonstrates the potential of this novel sorting technology to produce naturally contaminated diets with a large range of mycotoxin concentrations from a single wheat source to enable future investigations of mycotoxin exposure in any species.

Nondestructive Sugar-content Analysis for Cherry Tomatoes by Using Near-infrared Diffuse Transmittance Spectroscopy

Nondestructive Sugar-content Analysis for Cherry Tomatoes by Using Near-infrared Diffuse Transmittance Spectroscopy

Matrix Effects in Quantitative Assessment of Pharmaceutical Tablets Using Transmission Raman and Near-Infrared (NIR) Spectroscopy.

Raman spectroscopy can be an alternative to near-infrared spectroscopy (NIR) for nondestructive quantitative analysis of solid pharmaceutical formulations. Compared with NIR spectra, Raman spectra have much better selectivity, but subsampling was always an issue for quantitative assessment. Raman spectroscopy in transmission mode has reduced this issue, since a large volume of the sample is measured in transmission mode. The sample matrix, such as particle size of the drug substance in a tablet, may affect the Raman signal. In this work, matrix effects in transmission NIR and Raman spectroscopy were systematically investigated for a solid pharmaceutical formulation. Tablets were manufactured according to an experimental design, varying the factors particle size of the drug substance (DS), particle size of the filler, compression force, and content of drug substance. All factors were varied at two levels plus a center point, except the drug substance content, which was varied at five levels. Six tablets from each experimental point were measured with transmission NIR and Raman spectroscopy, and their concentration of DS was determined for a third of those tablets. Principal component analysis of NIR and Raman spectra showed that the drug substance content and particle size, the particle size of the filler, and the compression force affected both NIR and Raman spectra. For quantitative assessment, orthogonal partial least squares regression was applied. All factors varied in the experimental design influenced the prediction of the DS content to some extent, both for NIR and Raman spectroscopy, the particle size of the filler having the largest effect. When all matrix variations were included in the multivariate calibrations, however, good predictions of all types of tablets were obtained, both for NIR and Raman spectroscopy. The prediction error using transmission Raman spectroscopy was about 30% lower than that obtained with transmission NIR spectroscopy.

Pressurized polyol synthesis of Al-doped ZnO nanoclusters with high electrical conductivity and low near-infrared transmittance

In this study, a novel pressurized polyol method is proposed to synthesize aluminum-doped ZnO (AZO) nanoclusters without utilizing additional thermal treatment to avoid the merging of nanoclusters. The size of the AZO nanoclusters range from 100 to 150nm with a resistivity of 204Ωcm. The AZO nanoclusters primarily consist of approximately 10-nm nanocrystals that form a spherically clustered morphology. A two-stage growth model has been proposed based on the results of scanning electron microscopy and transmission electron microscopy images, nanocluster sizes, and X-ray diffraction patterns. The primary AZO nanocrystals first nucleate under pressurized conditions and then spontaneously aggregate into larger nanoclusters. Optically, the AZO nanoclusters exhibit a significant decrease in the near-infrared (NIR) transmittance compared to pure ZnO nanoparticles. The NIR blocking efficiency of AZO nanoclusters reached 85%. Moreover, the doping efficiency, resistivity, and NIR transmittance of AZO nanoclusters are influenced by the reaction time in the pressurized polyol solution. On the other hand, the reaction time has no effect on the particle size and crystallinity. An optically transparent coating for the AZO nanoclusters, which consisted of iso-propanol solvent and ultraviolet-curable acrylic binder, was also demonstrated.

Transparent conductive Nd-doped ZnO thin films

Transparent Nd-doped ZnO films with thickness in the range of 70 to 250 nm were grown by pulsed-laser deposition (PLD) on c-cut sapphire substrates at various oxygen pressures and substrate temperatures. A wide range of optical and electrical properties of the films were obtained and correlated to the composition and crystalline structure. The Nd-doped ZnO films are smooth, dense, and display the wurtzite phase. Different epitaxial relationships between films and substrate as a function of growth pressure and substrate temperature were evidenced by asymmetric x-ray diffraction measurements. By varying PLD growth conditions, the films can be tuned to have either metallic or semiconductor characteristics, with good optical transmittance in the visible range. Moreover, a low-temperature metal-insulator transition may be observed in Nd-doped ZnO films grown under low oxygen pressure. Resistivities as low as 6 × 10−4 Ω cm and 90% optical transmittance in the visible range and different near-infrared transmittance are obtained with approximately 1.0–1.5 at.% Nd doping and growth temperature of approximately 500 °C.

The use of near infrared transmittance kernel sorting technology to salvage high quality grain from grain downgraded due to Fusarium damage.

The mycotoxins associated with specific Fusarium fungal infections of grains are a threat to global food and feed security. These fungal infestations are referred to as Fusarium Head Blight (FHB) and lead to Fusarium Damaged Kernels (FDK). Incidence of FDK >0.25% will lower the grade, with a tolerance of 5% FDK for export feed grain. During infestation, the fungi can produce a variety of mycotoxins, the most common being deoxynivalenol (DON). Fusarium Damaged Kernels have been associated with reduced crude protein (CP), lowering nutritional, functional and grade value. New technology has been developed using Near Infrared Transmittance (NIT) spectra that estimate CP of individual kernels of wheat, barley and durum. Our objective is to evaluate the technology's capability to reduce FDK and DON of downgraded wheat and ability to salvage high quality safe kernels. In five FDK downgraded sources of wheat, the lowest 20% CP kernels had significantly increased FDK and DON with the high CP fractions having decreased FDK and DON, thousand kernel weights (TKW) and bushel weight (Bu). Strong positive correlations were observed between FDK and DON (r = 0.90); FDK and grade (r = 0.62) and DON and grade (r = 0.62). Negative correlations were observed between FDK and DON with CP (r = −0.27 and −0.32); TKW (r = −0.45 and −0.54) and Bu (r = −0.79 and −0.74). Results show improved quality and value of Fusarium downgraded grain using this technology.

가시광 및 근적외선 투과분광법을 이용한 감염 씨감자 온라인 선별시스템 개발

가시광 및 근적외선 투과분광법을 이용한 감염 씨감자 온라인 선별시스템 개발

Gallium codoping for high visible and near-infrared transmission in Al-doped ZnO thin films for industrial-scale applications

Transparent conductive oxide (TCO) materials have been constantly studied and developed in laboratory research scale, but few of them were successfully connected to the industrial production. One of main reasons is a lack of reproducibility of the high TCO performance due to the completely different fabrication conditions, equipment, and scale between academic science and industry. In this work, the authors report high visible and near-infrared transmission in Zn(Al,Ga)O thin films that were fabricated under suitable industrial conditions by using a large-scale, high-throughput in-line sputtering system. Zn(Al,Ga)O exhibits sheet resistance of ∼8.05 Ω/sq. and average optical transmittance of 92.07% in the visible region, with a figure of merit that is three times higher than that of ZnAlO. Zn(Al,Ga)O also shows high near-infrared transmittance tunability of more than 10% without significant change in the visible light transmittance, where the difference is &amp;lt;1%. The authors reveal the significant roles of Ga in both compensating for the degradation in the film crystallinity and suppressing the creation of crystal defects such as Al interstitials, ZnAl2O4 nanocluster precipitations, and grain boundaries. These results suggest high optoelectrical properties of Zn(Al,Ga)O thin film for industrial applications.

Study of the near-infrared transmission of woven fabrics based on statistical analysis

47 kinds of woven fabrics were prepared with different fibers, thicknesses, weights per square meter and percentage covers. Statistical analysis method was employed to study the influence of the material and structure parameters on near-infrared transmission of these fabrics. Firstly, the effect of materials on near-infrared transmittance was determined through the contingency table analysis. Then the parameters significantly influencing near-infrared transmittance were found out and correlations among them were discussed by direct correlation and partial correlation analysis. Finally, regression equation of the near-infrared transmittance was established using factor analysis and principal component extraction. Results show that materials have little influence on near-infrared transmittance of woven fabrics. However, thickness, weight per square meter and percentage cover of the fabrics are closely related to near-infrared transmittance. Because there are correlations among thickness, weight per square meter and percentage cover, two new factors are extracted to establish the regression equation. The equation has an error rate of less than 5 % and thus can predict near-infrared transmittance precisely.