Near-infrared Light Reflectance Research Articles

All-dielectric hybrid VIS-NIR dual-function metaoptic

Metasurfaces are a promising technology that can serve as a compact alternative to conventional optics while providing multiple functions depending on the properties of the incident light, such as the wavelength, polarization, and incident angle. Here, we demonstrate a hybrid visible/near-infrared dielectric metaoptic capable of reflecting 940 nm light in a specified direction while allowing transmission of visible light (450–750 nm). This dual functionality is achieved by combining an aperiodic distributed Bragg reflector with dielectric meta-atoms. Experimental demonstration is also reported, showing an anomalous reflection of near-infrared light within a 20° full field-of-view and the transmission of wavelengths from 450 nm to 750 nm.

Full-spectrum photocatalytic treatment and in situ upcycling of organophosphorus wastewater enabled by biomimetic urchin-like Bi2S3/CdS

High-efficiency photo-degradation organophosphorus pollutants into value-added chemicals, reducing or avoiding CO2 emission, is challenging but significant for environmental protection and carbon neutrality. Herein, a novel biomimetic urchin-like Bi2S3/CdS (BCS-UL) photocatalyst with full spectral response was developed for thorough degradation of glyphosate (Gly) and in situ upcycling into CO (731 μmol g-1h−1). Control experiments, finite element simulations, and theoretical calculations corroborated that Z-scheme heterojunction BCS-UL achieved highly photothermal/pyroelectric properties by multiple scattering and reflection of near-infrared light among spines of Bi2S3 component, which could promote the transfer of electron-hole pairs and regulate the selective formation of reactive oxygen species •O2–. The active center CdS component promoted C-P bond activation of Gly, which was more susceptible to being converted into sarcosine and further to CO by nucleophilic attack with •O2– and oxidation with h+. The decomposition pathways of Gly and acute toxicity of the intermediates were analyzed with LC-MS, Fukui index, and theoretical calculation. Moreover, BCS-UL was applicable for the efficient degradation of Gly at low concentrations over a wide pH range and could be recycled at least 5 times with no evident decline in catalytic activity. The biomimetic manufacturing technology provides a new avenue for implementing synchronously high-performance photocatalytic treatment and oriented upcycling of organic pollutants.

Design of functional coating with superior liquid repellency, self-cleaning, photodegradation and thermal insulation properties for building protection

A super-hydrophobic multifunctional coating (SMC) was designed and fabricated by combining commercial TiO2 with polydimethylsiloxane and perfluorodecyltrichlorosilane. The main objective of this research is to enhance the feasibility and effectiveness of SMC coating for building protection. After optimization, the comprehensive performance was significantly improved. The SMC not only significantly improves the water repellency of concrete (decreasing the capillary water absorption by 92.91 %), but also endows concrete with great self-cleaning and photodegradation properties. Additionally, ultraviolet–simulated (90 d) and practical environment (150 d) irradiation tests demonstrate the superior radiative cooling properties of SMC. COMSOL finite element simulation indicates about 20 % of ultraviolet light absorbance and 80 % of visible and near-infrared light reflectance on the SMC. The multifunctional SMC coating not only enhances the water repellency and self-cleaning properties of concrete, but also demonstrates excellent radiative cooling capabilities. These findings highlight the potential of the SMC coating as a promising material for sustainable and energy-efficient building applications.

Preparation of Flexible Liquid Crystal Films with Broadband Reflection Based on PD&SLC.

A simple and efficient method for the preparation of a film with flexible characteristic and selective reflection of near-infrared light is proposed. Based on the coexistence system (PD&SLC) of polymer dispersed liquid crystals (PDLC) and polymer stabilized liquid crystals (PSLC), it combines the flexibility of PDLC with the selectively reflection of PSLC. Innovative use of step-by-step light curing to achieve microstructural differences in the three-dimensional orientation of the material is proposed. That is, the difference between PDLC and PSLC in the planar orientation, as well as the gradient distribution of cholesteric phase liquid crystal pitch in the cell thickness direction, is observed. While realizing the flexibility of the material, the function of broadening the reflection bandwidth is fulfilled. This method of preparing liquid crystal films is expected to have great potential for applications, such as flexible smart windows, infrared light shielding, and sensors.

Optical Coherence Tomography in Cerebrovascular Disease: Open up New Horizons.

Optical coherence tomography (OCT), based on the backscattering or reflection of near-infrared light, enables an ultra-high resolution of up to 10μm. The successful application of OCT in coronary artery diseases has sparked increasing interest in its implementation in cerebrovascular diseases. OCT has shown promising potential in the atherosclerotic plaque structure characterization, plaque rupture risk stratification, pre-stenting and post-stenting evaluation, and long-term follow-up in extracranial and intracranial atherosclerotic stenosis (ICAS). In hemorrhagic cerebrovascular diseases, OCT plays an important role in the structure evaluation, rupture risk stratification, and healing and occlusion evaluation following initial treatment in intracranial aneurysms (IAs). In this study, we summarized the applications of OCT in the diagnosis, treatment, and follow-up of cerebrovascular diseases, especially in ICAS and IAs. The current limitations and future directions of OCT in the endovascular treatment of cerebrovascular diseases were also discussed.

Improving Soil Moisture Assessment of Turfgrass Systems Utilizing Field Radiometry

The need for water conservation continues to increase as global freshwater resources dwindle. Turfgrass mangers are adapting to these concerns by implementing new tools to reduce water consumption. Time-domain reflectometer (TDR) soil moisture sensors can decrease water usage when scheduling irrigation, but nonuniformity across unsampled locations creates irrigation inefficiencies. Remote sensing data have been used to estimate soil moisture stress in turfgrass systems through the normalized difference vegetation index (NDVI). However, numerous stressors other than moisture constraints impact NDVI values. The water band index (WBI) is an alternative index that uses narrowband, near-infrared light reflectance to estimate moisture limitations within the plant canopy. The green-to-red ratio index (GRI) is a vegetation index that has been proposed as a cheaper alternative to WBI as it can be measured using digital values of visible light instead of relying on more costly hyperspectral reflectance measurements. A replicated 2 × 3 factorial experimental design was used to repeatedly measure turf canopy reflectance and soil moisture over time as soils dried. Pots of ‘007’ creeping bentgrass (CBG) and ‘Latitude 36’ hybrid bermudagrass (HBG) were grown on three soil textures: United States Golf Association (USGA) 90:10 sand, loam, and clay. Reflectance data were collected hourly between 07:00 and 19:00 using a hyperspectral radiometer and volumetric water content (VWC) data were collected continuously using an embedded soil moisture sensor from soil saturation until complete turf necrosis by drought stress. The WBI had the strongest relationship to VWC (r = 0.62) compared to GRI (r = 0.56) and NDVI (r = 0.47). The WBI and GRI identified significant moisture stress approximately 28 h earlier than NDVI (p = 0.0010). Those metrics also predicted moisture stress prior to fifty percent visual estimation of wilt (p = 0.0317), with lead times of 12 h (WBI) and 9 h (GRI). By contrast, NDVI provided 2 h of prediction time. Nonlinear regression analysis showed that WBI and GRI can be useful for predicting moisture stress of CBG and HBG grown on three different soil textures in a controlled environment.

Single probe diffuse reflectance spectroscopy to assess the effect of sarcopoterium spinosum treatment on the cerebral tissue properties of ApoE knockout mouse.

In this work, diffuse near-infrared light reflectance spectroscopy based on a single optical probe, contains central single collection fiber surrounded by a circular array of illumination fibers, was used to quantify cerebral tissue properties in ApoE knockout mice following Sarcopoterium spinosum treatment. Sarcopoterium spinosum, also known as Thorny burnet, is a Mediterranean plant widely used as a traditional therapy for the treatment of a variety of pathologies, primarily type 2 diabetes mellitus (T2D). While it's efficacy in the treatment of T2D, and of other components of metabolic syndrome, have already been validated by us, the aim of this study was to investigate the effects of Sarcopoterium spinosum extract (SSE) on dyslipidemia and vascular functions. We utilized ApoE deficient mice (ApoE-/- , Atherosclerosis-prone apolipoprotein E-deficient), who have a severe impairment in plasma lipoprotein clearance and thus develop alterations in blood lipid profile and are highly susceptible to atherogenic plaque formation. A total of 34 male mice were divided into five groups representing various genetic, dietary, and treatment configurations. Optical measurements were used to assess changes in diffused reflectance spectra, optical properties (absorption and scattering), and cerebral tissue chromophore contents. Specifically, significant improvement in cerebral hemoglobin level was observed in ApoE KO mice, fed an artherogenic diet (ATD), upon SSE treatment. Biochemical and histological analyses of ApoE-/- ATD mice showed elevated body weight and a high level of blood triglycerides, free fatty acids and cholesterol. In contrast, in SSE treated mice improvement was observed, suggesting beneficial effects of SSE. In ApoE-/- ATD mice group a higher levels of deoxyhemoglobin was monitored indicating that the rate of oxygen release to the tissue is low. This was supported by decrease in oxygen saturation. It was also shown a reduction in water content in the brain of ApoE KO. Mice fed with the atherogenic diet demonstrated increased water content as compared to STD-fed ApoE KO mice, while SSE administration reversed the effect of the diet. To our knowledge, no such study has been reported before.

A novel approach toward reducing energy consumption and promoting electromagnetic interference shielding efficiency in the buildings using Brick/polyaniline nanocomposite

In this research, a complementary approach was presented to prepare building materials, improving shielding and energy efficiency. Accordingly, a macroporous Brick was constructed and coated by the polyaniline (PANi) film using an innovative route. Diverse analyses were applied, attesting Brick/PANi composite has been synthesized. The results of the diffuse reflection spectroscopy (DRS) analysis illustrated that the intensity of the light absorption in UV–Vis-NIR region was dramatically diminished for Brick/PANi, suggesting the nanocomposite for improving energy efficiency. Noticeably, the bandgap was augmented to 3.7 eV when Brick was coated by PANi. The warming samples were monitored using infrared thermometer under the near-infrared (NIR) light. Interestingly, the obtained results exhibited that the warming Brick/PANi nanocomposite was more time-consuming compared to Brick. More significantly, differential scanning calorimetry (DSC) thermograms attested that Brick/PANi nanocomposite needs lower energy to augment its temperature due to the coated PANi film (12 μm). The obtained results manifest that the reflection of NIR light from interface of PANi film plays the vital role in thermal behavior of Brick/PANi nanocomposite. Finally, Brick exposed significant shielding efficiency (SE) originated by its macroporous structure reinforcing interfacial polarization and the coated PANi film ascended its SE properties. The obtained results clarified that Brick/PANi nanocomposite has shielded more than 59% of the electromagnetic waves at x-band, which was mainly generated by relaxation and conductive loss produced by coated PANi and developed functional groups. More significantly, the absorption played vital role bringing SE of the samples, emphasizing the importance of the presented research.

Use of Vibrational Optical Coherence Tomography to Characterize Skin Lesions and a Congenital Nevus

We have used vibrational optical coherence tomography (VOCT) to image and measure the mechanical properties of normal skin and skin lesions. It is observed that in a congenital nevus and normal skin, the cellular epidermis is qualitatively not as bright as in skin lesions including basal cell carcinoma, actinic keratosis and a melanocytic nevus. Melanin and cytochrome c oxidase are reported to attenuate the reflection of near-infrared light at a wavelength of 810 nm and therefore may explain the reduced reflection of light in a congenital nevus and normal skin under conditions where cytochrome c oxidase levels would be expected to be high. Our results suggest that the melanin and cytochrome c oxidase levels found in congenital nevus and skin lesions may influence the observed pixel density observed in OCT images. For this reason, a correction for the content of these components in the skin must be considered before quantitative pixel measurements can be correctly interpreted. Additional measurements of pixel density along with the moduli of cellular and collagenous components in skin and skin lesions are needed to further interpret the significance of “virtual biopsies” made using VOCT.

Assessing changes in tissue oxygenation by near-infrared spectroscopy following brachial plexus block for arteriovenous fistula surgery: A prospective observational pilot study.

Near-infrared spectroscopy (NIRS) can be used to measure tissue oxygen saturation (StO2) in different sites and in a wide range of clinical scenarios. Peripheral regional anaesthesia induces vascular changes causing increased arterial blood flow and venodilatation, but its effect on StO2 is still under debate. This is especially so for patients undergoing arteriovenous fistula surgery, wherein latest data suggest an improved outcome under brachial plexus block (BPB) compared with local anaesthesia, but no data are available. The aim of this study was to investigate changes in StO2 following BPB prior to arteriovenous fistula surgery using NIRS. A prospective observational study. A secondary teaching hospital from August 2016 to March 2017. Fifteen patients undergoing arteriovenous fistula surgery. Ultrasound-guided BPB in 15 patients undergoing arteriovenous fistula surgery. StO2 at baseline and compared with baseline and the contralateral arm following BPB measured using NIRS of the thenar eminence (NIRSth). Baseline values of StO2 assessed by NIRSth were 42.6 ± 7.7% in the arteriovenous fistula arm and 42.7 ± 9.7% in the contralateral arm. There was no significant difference between the two. Five minutes after BPB, there was a significant increase in StO2 of the blocked arm, compared with the control arm expressed as difference of absolute values (7.1 ± 9.7%). At 60 min, an absolute difference of 21.0 ± 13.5% was reached. The absolute increase in StO2 of the blocked arm compared with baseline reached significance after 5 min (8.8 ± 4.6%) and increased up to 23.2 ± 8.2% after 60 min. NIRSth indicates that BPB significantly increases StO2 of the arteriovenous fistula arm in patients undergoing haemodialysis. Clinicaltrials.gov: NCT03044496.

Reflection of near-infrared light confers thermal protection in birds

Biologists have focused their attention on the optical functions of light reflected at ultraviolet and human-visible wavelengths. However, most radiant energy in sunlight occurs in ‘unseen’ near-infrared (NIR) wavelengths. The capacity to reflect solar radiation at NIR wavelengths may enable animals to control heat gain and remain within their critical thermal limits. Here, using a continent-wide phylogenetic analysis of Australian birds, we show that species occupying hot, arid environments reflect more radiant energy in NIR wavelengths than species in thermally benign environments, even when controlling for variation in visible colour. Biophysical models confirm that smaller species gain a greater advantage from high NIR reflectivity in hot, arid environments, reducing water loss from compensatory evaporative cooling by up to 2% body mass per hour. These results highlight the importance of NIR reflectivity for thermal protection, which may become increasingly critical as the frequency of extreme climatic events increases.

근적외선 반사 박막 특성 연구

Abstract Near infrared blocking function in energy saving window glass is required. The design, deposition and characteristics of optical thin films for reflection of near-infrared light were studied. The optical thin film is designedas laminated film structure with low refractive index film and high index film. Deposition experiments of SiO 2 and TiO 2 thin films with designed structure using the RF sputtering method were carried out. The characteristics of thethin film with deposition conditions were analyzed. High-refractive-index thin film of TiO 2 /low refractive-index thinfilm of SiO 2 and high-refractive-index thin film of TiO 2 structure for reflection of near-infrared light was designed to be simulated. Results of simulation showed reflectance of 30% or more in the range from 930nm to 1682nm. Triplelayer thin films fabricated with simulated results showed wavelength bands from 930nm to 1525nm for the reflectanceof 33% or more. Key Words : Near infrared, Reflection, Thin film 본 연구는 한경대학교 2014년도 학술연구조성비의 지원에 의한 것임 (This work was supported by a research grant from Hankyong National University in the year of 2014.)

Randomness in highly reflective silver nanoparticles and their localized optical fields.

Reflection of near-infrared light is important for preventing heat transfer in energy saving applications. A large-area, mass-producible reflector that contains randomly distributed disk-shaped silver nanoparticles and that exhibits high reflection at near-infrared wavelengths was demonstrated. Although resonant coupling between incident light and the nanostructure of the reflector plays some role, what is more important is the geometrical randomness of the nanoparticles, which serves as the origin of a particle-dependent localization and hierarchical distribution of optical near-fields in the vicinity of the nanostructure. Here we show and clarified the unique optical near-field processes associated with the randomness seen in experimentally fabricated silver nanostructures by adapting a rigorous theory of optical near-fields based on an angular spectrum and detailed electromagnetic calculations.

Study of Stored Product Insects Identification Based on near Infrared Spectroscopy (NIRS)

The harm of stored product pests are very serious, which caused huge losses to the national economy. It is important to strengthen the research on the insects, for the protection of reservoir storage and quarantine. In the recognition of stored product insects, Some insects have anabiosis, once it is missed, if the external environment is favorable, it will flourish and spread, there will be great harm to the storage of food. This paper briefly introduces the basic principle of the near infrared spectroscopy technology combined with the basic principle of digital image processing and recognition technology. The basic principle of automatic identification technology of dead and live insects, it is based on the difference of absorption and reflection of near-infrared light for the identification of insect pests. This paper presents a new idea of research on near infrared spectroscopy technology and digital image processing technology for automatic identification of direction in the dead and live insects.

Estimating the absorption coefficient of the bottom layer in four-layered turbid mediums based on the time-domain depth sensitivity of near-infrared light reflectance

Expanding our previously proposed "time segment analysis" for a two-layered turbid medium, this study attempted to selectively determine the absorption coefficient (μa) of the bottom layer in a four-layered human head model with time-domain near-infrared measurements. The difference curve in the temporal profiles of the light attenuation between an object and a reference medium, which are obtained from Monte Carlo simulations, is divided into segments along the time axis, and a slope for each segment is calculated to obtain the depth-dependent μa(μaseg). The reduced scattering coefficient (μs') of the reference is determined by curve fitting with the temporal point spread function derived from the analytical solution of the diffusion equation to the time-resolved reflectance of the object. The deviation of μaseg from the actual μa is expressed by a function of the ratio of μaseg in an earlier time segment to that in a later segment for mediums with different optical properties and thicknesses of the upper layers. Using this function, it is possible to determine the μa of the bottom layer in a four-layered epoxy resin-based phantom. These results suggest that the method reported here has potential for determining the μa of the cerebral tissue in humans.

Monitoring hemodynamic and morphologic responses to closed head injury in a mouse model using orthogonal diffuse near-infrared light reflectance spectroscopy

The authors' aim is to assess and quantitatively measure brain hemodynamic and morphological variations during closed-head injury (CHI) in mice using orthogonal diffuse near-infrared reflectance spectroscopy (o-DRS). CHI is a type of injury to the head that does not penetrate the skull. Usually, it is caused by mechanical blows to the head and frequently occurs in traffic accidents, falls, and assaults. Measurements of brain optical properties, namely absorption and reduced scattering coefficients in the wavelength range from 650 to 1000 nm were carried out by employing different source-detector distance and locations to provide depth sensitivity on an intact scalp over the duration of the whole experiment. Furthermore, alteration in both cortical hemodynamics and morphologic markers, i.e., scattering power and amplitude properties were derived. CHI was induced in anesthetized male mice by a weight-drop model using ∼50 g cylindrical metal falling from a height of 90 cm onto the intact scalp producing an impact of 4500 g cm. With respect to baseline, difference in brain physiological properties was observed following injury up to 1 h post-trauma. Additionally, the reduced scattering spectral shapes followed Mie scattering theory was quantified and clearly shows changes in both scattering amplitude and power from baseline indicating structural variations likely from evolving cerebral edema during CHI. We further demonstrate high correlation between scattering amplitude and scattering power, with more than 20% difference in slope in comparison to preinjury. This result indicates the possibility of using the slope also as a marker for detection of structural changes. Finally, experiments investigating brain function during the first 20 min postinjury were conducted and changes in chromophore concentrations and scattering were observed. Overall, our experiments demonstrate the potential of using the proposed technique as a valuable quantitative noninvasive tool for monitoring brain physiology following CHI injury at the bedside and/or at the field.

The use of near-infrared light for safe and effective visualization of subsurface blood vessels to facilitate blood withdrawal in children

Obtaining access to blood vessels can be difficult, especially in children. Visualization of subsurface blood vessels might be a solution. Ultrasound and visible light have been used to this purpose, but have some drawbacks. Near-infrared light might be a better option since subsurface blood vessels can be visualized in high contrast due to less absorption and scattering in tissue as compared to visible light. Our findings with a multispectral imaging system support this theory.A device, the VascuLuminator, was developed, based on transillumination of the puncture site with near-infrared light. The VascuLuminator was designed to meet the requirements of compact and safe use. A phantom study showed that the maximum depth of visibility (5.5mm for a 3.6mm blood vessel) is sufficient to visualize blood vessels in typical locations for peripheral venous and arterial access. A quantitative comparison of the VascuLuminator and to two other vessel imaging devices, using reflection of near-infrared light instead of transillumination, was conducted. The VascuLuminator is able to decrease failure at first attempt in blood withdrawal in pediatric patients from 10/80 (13%) to 1/45 (2%; P=.05).

Chronic Total Occlusions: Experience with Fiber‐Optic Guidance Technology — Optical Coherence Reflectometry

Chronic total occlusions are difficult to treat and continue to challenge the interventional cardiologist. The primary difficulty is safely crossing the total occlusion with a guidewire before any revascularization can begin. One of the main reasons conventional and newer guidewires have not proven effective is simply the lack of visualization to safely steer the guidewire across the occlusion. This limitation can be overcome with new technology using a "forward-looking" fiber-optic guidance. The Safe-Steer TO (Total Occlusion) Crossing System is a new guidance system that uses optical coherence reflectometry to steer a guidewire through total occlusions. Optical coherence reflectometry uses algorithms to determine tissue types (plaque vs arterial wall) by measuring the intensity of the reflection of near-infrared light. The authors' clinical experience with the Safe-Steer System has met considerable success. With their initial 28 patients (7 women, 21 men) with known chronic total occlusions and confirmed ischemia, the primary success rate for the crossing the occlusion was 86% (24/28 cases). The average occluded lesion length was 41.1 +/- 30.8 mm. Our initial clinical experience demonstrates that the optical guidewire is a viable technology in the treatment of chronic total occlusions.

In situ Near-IR Cure Monitoring of a Model Epoxy Matrix Composite

To improve the performance of composites it is imperative that the interphase region between the inorganic reinforcement and the polymer matrix be more completely understood. It is in this region that the stress transfer between the matrix and the reinforcement occurs. To this end, the curing of epoxy adjacent to an embedded silica optical fiber has been monitored in situ by evanescent wave spectroscopy. The epoxy studied is partially fluorinated and has a lower refractive index than the silica optical fiber. This combination of epoxy/silica served as a model composite system. The lower refractive index of the partially fluorinated epoxy allowed the silica optical fiber to be used as a waveguide for the internal reflection of near-infrared light. The epoxy curing was determined as a function of time and temperature by analysis of the near-infrared spectrum from the epoxy adjacent to the fiber obtained by the interaction of the evanescent wave that occurs at each internal reflection with the low-refractive-index epoxy. The results obtained from the examination of the near-infrared spectrum, particularly the disappearance of the NH2 stretching/bending combination band at ∼4925 cm−1 and the concomitant increase of the C–N overtone band at ∼4725 cm−1, showed that epoxy ring-opening and cross-linking reactions could be followed in real time. Finally, treatment of the fiber with a silane coupling agent had no observable effect on the curing reaction of the epoxy.

The influence of ammonia-induced cellulardiscoloration within cotton leaves ( Gossypium hirsutum L.) on light reflectance, transmittance, and absorptance

Cellular discoloration within cotton leaves, caused by ammoniatreatment, reduced spectrophotometrically measured near-infrared light reflectance over the wavelength interval 750–900 mμ, where rounding of the plateau occurred. Results with ammonia-treated leaves are compared with other studies in which reduced reflectance occurred over the 750–900 mμ wavelength interval. It is possible that this rounding of the plateau caused by internal cellular discoloration may become useful in remote sensing for identifying certain nonvisual symptoms of plant leaf stresses caused by cellular discoloration.