Near-infrared Transmittance Research Articles

Measurement of quality parameters of sugar beet juices using near-infrared spectroscopy and chemometrics

Near-infrared transmittance spectroscopy combined with multivariate chemometric was investigated in the present work to predict the Polarization (Pol), soluble solids content (°brix), sucrose concentration and pH value of raw, thin and thick sugar beet juices (SBJs). All samples were scanned to obtained spectral information in the wavelength range of 860–1800 nm. The impacts of various pre-processing and spectra treatment methods, such as standard normal variate transformation (SNV), Moving Average (MA) and area normalization (AN) were also investigated. Partial least squares (PLS) regression was introduced to develop the calibration model relating quality parameter values to spectral data. Accordingly, the results show that the PLS models were acceptable for predicting the pol (R2 = 0.969), °brix (R2 = 0.984), sucrose (R2 = 0.921) and slightly pH value (R2 = 0.671) in SBJ samples. Results suggest that the near-infrared spectroscopy coupled with the PLS regression method can become a useable and fast tool for evaluation of quality parameters in SBJs.

Solution processed W-doped In2O3 thin films with high carrier mobility

Transparent conducting (TC) donor-doped In2O3 thin films are the critical components in photovoltaic, display and solid-state lighting fields. In2O3-based TC films with high carrier mobility are required for reducing the power consumption of devices. Meanwhile, a high near-infrared (NIR) transparency can significantly improve the power conversion efficiency in solar cells. Here, W-doped In2O3 thin films with high carrier mobility and NIR transparency were obtained through a facile solution process, which is suitable for large-scale thin film fabrication. The effects of W concentration (0.3 at% to 0.7 at%) on the microstructures, electrical and optical properties of In2O3 thin films are investigated in detail. It is found that the 0.5% W-doped In2O3 thin film exhibits high carrier mobility of 23 cm2 V−1 s−1 at a carrier concentration of 5.02 × 1020 cm−3, showing a high NIR transmittance over 82% and low sheet resistance of 32 Ω/sq. The solution processed W-doped In2O3 thin films with low sheet resistance and high NIR transparency can be potentially used as transparent electrodes for solar cells.

Experimental study of the phase behavior of methane and crude oil mixtures

Phase behavior of reservoir fluids is crucial for an efficient production development project. In this paper, a new dataset of phase transitions of Brazilian pre-salt crude oil mixed with methane systems is presented and phase behavior discussed under different analytical technics. A series of mixtures of a dead crude (API 28.0, 0.68 wt% of asphaltenes) with 65.0, 67.5, 70.0, 72.5, and 75.0 mol% of methane were studied by constant mass expansion in a PVT cell, coupled with a high-pressure microscopy (HPM). Pressure-volume data shows slight phase transition, with a not evident break due to difference on compressibility, specially by increasing methane molar content. For this reason, beside of visual observation, a near-infrared (NIR) transmittance was used for a proper identification of bubble point pressure. NIR transmittance also allow the detection of phase transitions above bubble point, that was confirmed by intermediate of by HPM analysis. A dispersion of fine particles was detected, and it was associated with asphaltenes onset, for the systems with high content of gas (72.5 and 75.0 mol% of methane). NIR transmittance along with micrographs taken during system pressurization confirm a low asphaltene hysteresis redissolution, with no flocs and mayor aggregates formation and rapid redissolution after system pressurization. This phenomenon could be related to the low content of asphaltenes on the crude oil sample.

Microstructural freezing of highly NIR transparent Y2O3-MgO nanocomposite via pressure-assisted two-step sintering

Y2O3-MgO nanocomposite has attracted attention for use in infrared windows and domes. However, the large difference in refractive index between the two phases of this materials phases induces inevitable grain boundary scattering. To overcome this drawback, it is indispensable to greatly reduce the grain size and eliminate residual pores. Two-step sintering has been extensively used to produce fine-grained ceramics, but long incubation time and an additional process are required. As a robust approach, pressure-assisted two-step consolidation of Y2O3-MgO nanocomposite ceramics is investigated to achieve full density while retaining domain size. A sintering path for pressure-assisted two-step sintering and related kinetic window are obtained for the first time. By effectively suppressing grain growth and eliminating residual pores via two-step hot-pressing, outstanding mid- and near-infrared transmittance were achieved. The results indicate that pressure-assisted two-step sintering is a promising alternative strategy that can decrease the domain size and achieve full density of ceramics.

Dual-response and Li+-insertion induced phase transition of VO2-based smart windows for selective visible and near-infrared light transmittance modulation

Chromogenic materials are widely used in the field of smart window with controllable throughput of solar energy and visible light. However, single modulation mode is often difficult to meet practical applications. Herein, we construct a novel multilayer device by effectively integrating thermochromic (TC) and electrochromic (EC) materials to selectively modulate visible and near-infrared (NIR) transmittance. The all-solid-state VO2-based multilayer device consists of VO2/LiTaO3/WO3 sandwich structure, with transparent conductor FTO and ITO as bottom electrode and top electrode, respectively. Therefore, this five-layer structure realized four reversible optical states, that is, TC layer passively responds to environmental temperature, while EC layer actively responds to external voltage simultaneously. Moreover, reversible migration of Li+ within the lattice of VO2 is achieved with a low voltage (just 3 V bias), which has an obvious effect (over 10 °C) on its phase change temperature (PCT). Finally, this novel dual-response VO2-based multilayer device provide a new strategy for VO2-based smart window applications.

Dual-beam spectral measurement improves accuracy of nondestructive identification of internal rot in onion bulbs

Visible and near-infrared transmittance spectroscopy is useful for detecting internal rot in onion bulbs, but it has limitations for accurate identification of bulbs with mild rot occurring locally in the neck region. We have developed a dual-beam system that measures the transmission spectra in two directions: the neck region (beamline 1: BL1) and across the equator (beamline 2: BL2) when placing an onion with its neck facing upward. Binary classification based on rot scores predicted by partial least squares regression (PLSR) models revealed that the sensitivity of detecting mildly rotten bulbs was superior in a PLSR model developed using the BL1 spectra, whereas the specificity for detecting sound (non-rotten) bulbs and the sensitivity for moderately-to-severely rotten bulbs were better in a PLSR model built using the BL2 spectra. A combined BL1 & BL2 spectra model, constructed using spectra in both directions simultaneously, retained the advantages of both spectra and improved the accuracy of detecting sound and mildly rotten bulbs. Furthermore, we developed a rot-detection threshold optimization procedure that minimized the sum of rates at which decayed bulbs were misidentified as being sound and sound bulbs were misidentified as being decayed, resulting in improved diagnostic performance under real-world conditions.

Quantification of Inkjet-Printed Pharmaceuticals on Porous Substrates Using Raman Spectroscopy and Near-Infrared Spectroscopy.

The use of inkjet printing for pharmaceutical manufacturing is gaining interest for production of personalized dosage forms tailored to specific patients. As part of the manufacturing, it is imperative to ensure that the correct dose is printed. The aim of this study was to use inkjet printing for manufacturing of personalized dosage forms combined with the use of near-infrared (NIR) and Raman spectroscopy as complementary analytical techniques for active pharmaceutical ingredient (API) quantification of the inkjet-printed dosage forms. Three APIs, propranolol (0.5-4.1mg), montelukast (2.1-12.1mg), and haloperidol (0.6-4.1mg) were inkjet printed in 1cm2 areas on a porous substrate. The printed doses were non-destructively analyzed by transmission NIR and Raman spectroscopy (both transmission and backscatter). X-ray computed microtomography (μ-CT) analysis was undertaken for porosity measurements of the substrate. The API content was confirmed using high-performance liquid chromatography (HPLC), and the content in the dosage forms was modeled from the NIR and Raman spectra using partial least squares regression (PLS). HPLC analysis revealed a linear correlation of the number of layers printed to the API content. The resulting PLS models for both NIR and Raman had R2 values between 0.95 and 0.99. The best predictive model was obtained using NIR, followed by Raman spectroscopy. μ-CT revealed the substrate to be highly porous and optimal for inkjet printing. In conclusion, NIR and Raman spectroscopic techniques could be used complementary as fast API quantification tools for inkjet-printed medicines.

An exploration of the combined effects of NIR and VIS spectrally selective thermochromic materials on building performance

Thermochromic (TC) windows are able to adjust solar radiation transmitted into buildings in response to varying window surface temperature. Vanadium Dioxide (VO2) is the most common TC material used for TC windows, as it can reduce near infrared (NIR) solar transmittance to attenuate undesirable solar heat gains during hot days when window surface temperature rises above a particular transition temperature. However, there have been few studies of the effect of TC windows on the indoor luminous environment. In order to improve daylight control, an innovative Iron-liquid based TC window film, which can control the visible (VIS) spectrum was introduced and applied alongside a VO2 based TC material in this study. The combined performance of these two types of TC material was evaluated under three climatic conditions within China: Beijing, Shanghai and Guangzhou. The results show that increasing either the NIR or visible transmittance difference after switching, is beneficial for thermochromic performance, the maximum energy saving increasing from 11% to 18%, and UDI500–2000 lx increasing by up to 27%. Combined application of NIR and visible spectral selection results in improved balance between energy demand and daylight provision. It was found that the energy saving potential and daylighting regulating capability offered by the combined implementation is highly dependent on matching the climate conditions to the TC windows.

Electrophoretic deposition of reduced graphene oxide thin films for reduction of cross-sectional heat diffusion in glass windows

Abstract Effective management of heat transfer, such as conduction and radiation, through glass windows is one of the most challenging issues in smart window technology. In this work, reduced Graphene Oxide (rGO) thin films of varying thicknesses are fabricated onto Fluorine-doped Tin Oxide (FTO) glass via electrophoretic deposition technique. The sample thicknesses increase with increasing number of deposition cycles (5, 10, 20 cycles). It is hypothesized that such rGO thin films, which are well-known for their high thermal conductivities, can conduct heat away laterally towards heat sinks and reduce near-infrared (NIR) transmittance through them, thus effectively slowing down the temperature increment indoors. The performance of rGO/FTO in reducing indoor temperatures is investigated with a solar simulator and a UV-Vis-NIR spectrophotometer. The 20-cycles rGO thin films showed 30% more NIR blocked at 1000 nm as compared to clean FTO, as well as the least temperature increment of 0.57 °C following 30 min of solar irradiation. Furthermore, the visible transmittance of the as-fabricated rGO films remain on par with commercial solar films, enabling up to 60% of visible light transmittance for optimal balance of transparency and heat reduction. These results suggest that the rGO thin films have great potential in blocking heat transfer and are highly recommended for smart window applications.

Construction of ultraviolet protection, thermal insulation, superhydrophobic and aromatic textile with Al-doped ZnO–embedded lemon microcapsule coatings

Multifunctional textiles combining ultraviolet protection, thermal insulation and superhydrophobic and aromatic performance were successfully prepared using an aluminum-doped zinc oxide (AZO)-embedded lemon microcapsule and SiO2 dual-layer coating. AZO-loaded lemon microcapsules with average diameter of 1.5 µm were obtained via interfacial polymerization. Results showed that the high concentration of the AZO-embedded lemon microcapsule contributed to enhancing the waterproof property, aromatic performance, and visible and near-infrared light transmittance. The lemon content was up to 2.789 mg/g (weight of essence:weight of fabric). The water contact angle was high at 153.35°, exhibiting an outstanding superhydrophobic performance. The light transmittance decreased as the amount of AZO-embedded lemon microcapsule increased. The ultraviolet protection factor value reached 88.78 when the dosage of the AZO-embedded lemon microcapsule was 6%. Given the above research results, the cotton fabric coated with the AZO-embedded lemon microcapsule and SiO2 dual-layer composite coating would have potential applications in the water/oil purification field and functional protective fabrics.

A Visible Light-Near-Infrared Dual-Band Smart Window with Internal Energy Storage

Summary The integration of electrochromic smart windows with energy storage is an appealing concept for green building development. Herein, we report a dual-band electrochromic energy storage (DEES) window capable of independent control of visible light (VIS) and near-infrared (NIR, solar heat) transmittance with a high internal charge storage. The key design feature is the use of composition-optimized Ta-doped nano-TiO2 nanocrystals as a multifunctional active material to deliver a high charge-storage capability concurrently with high bistability and long-cycle-life electrochromism in three distinct operating modes: (1) the VIS and NIR transparent “bright” mode; (2) the VIS transparent and NIR opaque “cool” mode; and (3) the completely opaque “dark” mode. The independent control of VIS (sunlight) and NIR (solar heat) modulation was successfully demonstrated in a DEES prototype with a high charge-storage capacity of 466.5 mA hr m−2 at 150 mA m−2 of current density.

Near-infrared transmittance enhancement using fully conformal antireflective structured surfaces on microlenses fabricated by direct laser writing

Structured surfaces composed of subwavelength-sized features offer multifunctional properties including antireflective characteristics that are increasingly important for the development of micro-optical components. Here, three-dimensional (3-D) direct laser writing, via two-photon polymerization, is used to fabricate planoconvex spherical microlenses with antireflective structured surfaces. The surfaces are composed of subwavelength-sized conicoid structures, which are arranged fully conformal to the convex surface of the microlenses. The dimensions of the conicoid structures are optimized to effectively reduce Fresnel reflection loss over a wide band in the near-infrared spectral range from 1.4 to 2.2 μm, with a maximum reduction at 1.55 μm. Infrared reflection and transmission measurements are used, in combination with 3-D finite element calculations, to investigate the performance of the microlenses. The experimental results reveal that in the spectral range from 1.4 to 2.2 μm an effective suppression of the Fresnel reflection loss at the convex surface of spherical microlenses can be achieved. The transmittance enhancement is ranging from 1% to 3% for spherical microlenses with antireflective structured surfaces, in comparison to an uncoated reference.

Fluid Inclusion Studies in Opaque Ore Minerals: I. Trace Element Content and Physical Properties of Ore Minerals Controlling Textural Features in Transmitted Near-Infrared Light Microscopy

Physical properties and compositions of ore-forming fluids in magmatic-hydrothermal systems have been mostly investigated by conventional fluid inclusion studies in transparent gangue minerals that are assumed to be “co-genetic” with the mineralization. However, ore precipitating fluids can be directly studied by analyzing fluid inclusions in opaque ore minerals, such as wolframite, stibnite, pyrite and enargite, by using near-infrared (NIR) petrography and microthermometry in combination with laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis of individual inclusions. Although results of NIR fluid inclusion studies of ore minerals were first published in 1984, the technique is still not commonly used in fluid inclusion research due to a number of limitations related to the analytical equipment used, sample preparation and NIR mineral transmittance. In this contribution we present new data on the applicability of NIR fluid inclusion studies in ore minerals (pyrite, stibnite, enargite, and wolframite) from a series of magmatic-hydrothermal systems, according to their chemical composition and physical behavior during microthermometry. Our results reveal strong correlation between NIR transmittance and high trace element (Co, Ni, Cu, As) content in pyrite, enargite (Fe, Bi), and wolframite (Sc, V, Fe). Despite this, the restricted distribution of these elements in oscillatory and sector zoning has allowed observation of NIR mineral features and fluid inclusions. Energy absorption of opaque minerals, either as light energy during microscopy or as thermal conductive energy during fluid inclusion microthermometry, presents a second limitation for NIR fluid inclusion studies. Our results confirm the relevance of fluid inclusion studies in ore minerals by combining NIR microscopy and microthermometry. Despite some limitations due to trace element composition of the host mineral and its physical behavior at high temperature, a successful NIR fluid inclusion study can be performed on some ore minerals that are opaque in the visible light range, allowing the direct study of hydrothermal ore-forming fluids.

Elucidating the Crystallite Size Dependence of the Thermochromic Properties of Nanocomposite VO2 Thin Films.

Fenestration elements that enable spectrally selective dynamic modulation of the near-infrared region of the electromagnetic spectrum are of great interest as a means of decreasing the energy consumption of buildings by adjusting solar heat gain in response to external temperature. The binary vanadium oxide VO2 exhibits a near-room-temperature insulator–metal electronic transition accompanied by a dramatic modulation of the near-infrared transmittance. The low-temperature insulating phase is infrared transparent but blocks infrared transmission upon metallization. There is considerable interest in harnessing the thermochromic modulation afforded by VO2 in nanocomposite thin films. However, to prepare a viable thermochromic film, the visible-light transmittance must be maintained as high as possible while maximizing thermochromic modulation in the near-infrared region of the electromagnetic spectrum, which necessitates the development of high-crystalline-quality VO2 nanocrystals of the optimal particle size embedded within the appropriate host matrix and refractive index matched to the host medium. Here, we demonstrate the preparation of acrylate-based nanocomposite thin films with varying sizes of embedded VO2 nanoparticles. The observed strong size dependence of visible-light transmittance and near-infrared modulation is explicable on the basis of optical simulations. In this article, we elucidate multiple scattering and absorption mechanisms, including Mie scattering, temperature-/phase-variant refractive-index mismatch between VO2 nanocrystals and the encapsulating matrix, and the appearance of a surface plasmon resonance using temperature-variant absorptance and diffuse transmittance spectroscopy measurements performed as a function of particle loading for the different sizes of VO2 nanocrystals. Nanocrystals with dimensions of 44 ± 30 nm show up to >32% near-infrared energy modulation across the near-infrared region of the electromagnetic spectrum while maintaining high visible-light transmission. The results presented here, providing mechanistic elucidation of the size dependence of the different scattering mechanisms, underscore the importance of nanocrystallite dimensions, refractive-index matching, and individualized dispersion of particles within the host matrix for the preparation of viable thermochromic thin films mitigating Mie scattering and differential refractive-index scattering.

Multifunctional Silica Nanotube Aerogels Inspired by Polar Bear Hair for Light Management and Thermal Insulation

Designing macroscopic, 3D porous multifunctional materials is of great importance in many fields, including energy storage, thermal insulation, sensors, and catalysis. Polar bears have hairs with a membrane-pore structure, which contributes to adaptation to harsh environments. Inspired by polar bear hair, this study reports a facile route to fabricate multifunctional silica nanotube aerogels (SNTAs) via chemical vapor deposition (CVD) of silica onto the sacrificial carbon nanoskeleton of a carbon aerogel (CA). The resulting SNTAs are not only porous, nanotubular, transparent, and lightweight but also hydrophobic, thermal resistant, mechanically robust, and machinable. Moreover, SNTAs show relatively high visible and near-infrared light transmittance and almost no ultraviolet and far-infrared light transmittance, which makes it an ideal material to provide greenhouse effects and protect human beings from an overdose of ultraviolet radiation. Multifunctional SNTAs provide an integrated solution for thermal ...

High efficiency 4-terminal perovskite/c-Si tandem cells

The perovskite/c-Si tandem technology is considered as a cost-effective approach to realize a cell efficiency beyond the limit of single-junction (SJ) c-Si cells. Compared to its counterpart of 2-terminal (2T) configuration, 4-terminal (4T) tandem has the advantages such as no constraint of current matching and potentially simple mechanical stacking. But one of the largest challenges is the limited near-infrared (NIR) transmission of the semi-transparent perovskite solar cell (ST-PSC), which has been a bottleneck to the c-Si bottom cell performance and eventually the whole tandem cell performance. The highest NIR transmittance that has been reported is about 84%. In this contribution, we demonstrate a p-i-n planar ST-PSC with an efficiency as high as 15.7% and with a record NIR transmittance of about 92%. It is realized by optimization of the tin-doped indium oxide (ITO) material properties and light management. This NIR-transparent and high-efficiency ST-PSC leads to a 4T tandem cell efficiency of 25.7%, using an interdigitated-back-contact (IBC) c-Si bottom cell.

Fast authentication of tea tree oil through spectroscopy

Two new procedures, based on infrared spectroscopy in the near infrared (NIR) and mid infrared (MIR), have been developed for the authentication of tea tree oil (TTO) commercial samples. Infrared measurements were made on untreated samples by transmission NIR and attenuated total reflectance (ATR) followed by partial least square discriminant analysis (PLS-DA). These methods offer a fast and low cost alternative to enantiomeric two-dimensional gas chromatography coupled to mass detection usually employed to discriminate between authentic and non-authentic samples. In these studies, a set of 267 samples, including authentic and non-authentic labelled tea tree oil samples, were used to build the models based on the wavenumber range, data pre-processing and latent variables number selection. Infrared methods can be discriminant for authentic and non-authentic TTO samples with a 98% certainty for both ATR and NIR methodologies, employing 92 and 142 external samples respectively. Developed PLS-DA infrared based methodologies and the reference methodology have been evaluated and compared from a Green Analytical point of view.

Fluoride-Assisted Synthesis of Plasmonic Colloidal Ta-Doped TiO2 Nanocrystals for Near-Infrared and Visible-Light Selective Electrochromic Modulation

Dual-band electrochromic materials are integral to the development of smart windows where visible and near-infrared (NIR) light transmittance may be individually controlled. We present here colloidal Ta-doped TiO2 anatase nanocrystals (NCs) as a promising candidate and their preparation by a fluoride-assisted synthesis method. The dual-band electrochromic performance of these NCs may be credited to their strong localized surface plasmon resonance (LSPR) absoption in the NIR region. The Ta doping of the TiO2 NC host, which has not been attempted before, is made easy in the presence of the fluoride anions. The synthesis produces Ta-doped TiO2 NCs as a highly uniform colloidal solution. Spectroscopic measurements indicate the generation of free carriers in the TiO2 conduction band by the Ta5+ substitution of Ti4+ cations as the origin of the LSPR. Good dual-band electrochromic performance in terms of a high dynamic range for visible and near-infrared light modulation (86.3% at 550 nm and 81.4% at 1600 nm) an...

English

Rice quality is measured of the rice grown on different five locations by an auto grain analyzer. Auto Grain analyzer works on the Near-Infrared transmittance (720 - 1100 nm). Protein, amylose and moisture contents of the rice samples of 9 fine lines were tested. Different environment tested entries were evaluated and found that all the values have highly significant effect of environment and genotypes. The environment and genotype ranking in the Additive Main effect and Multiplicative Interaction (AMMI) model were studied and PK8680-13-3-1 and check variety Basmati 515 were found most stable lines in most micro environment with respect to amylose contents and moisture contents. Protein contents were studies in PK8892-4-2-1-1 and PK3810-30-1 are best suited in the all environments. The results indicated that grain analyzer may be used for Amylose and Protein contents and effect of different locations on these traits in early breeding generations for quality control in the food industry.   Key words: Rice, environment, amylose, protein, auto grain analyzer.

High near-infrared transmittance and waveguide structures in polycrystalline ZnSe by carbon and proton implantation combined with photolithography

We report on near-infrared (NIR) waveguide structures in polycrystalline ZnSe using the carbon ion implantation technique combined with standard lithography. High NIR transmittance is observed by the absorption spectra before and after carbon and proton implantation at room temperature. Two half-Gaussian curves are used to reconstruct the refractive index profile of the waveguides at a wavelength of 1539 nm. The results show that the numerically simulated mode by the finite difference beam propagation method (FD-BPM) is in good agreement with the experimental data by end-facet setup, which exhibits a high potential for designable NIR waveguide devices in polycrystalline ZnSe by carbon ion implantation.