Wavelength Of Visible Light Research Articles

The Integrative Biology of Pigment Organelles, a Quantum Chemical Approach.

Coloration is a complex phenotypic trait involving both physical and chemical processes at a multiscale level, from molecules to tissues. Pigments, whose main property is to absorb specific wavelengths of visible light, are usually deposited in specialized organelles or complex matrices comprising proteins, metals, ions, and redox compounds, among others. By modulating electronic properties and stability, interactions between pigments and these molecular actors can lead to color tuning. Furthermore, pigments are not only important for visual effects but also provide other critical functions, such as detoxification and antiradical activity. Hence, integrative studies of pigment organelles are required to understand how pigments interact with their cellular environment. In this review, we show how quantum chemistry, a computational method that models the molecular and optical properties of pigments, has provided key insights into the mechanisms by which pigment properties, from color to reactivity, are modulated by their organellar environment. These results allow us to rationalize and predict the way pigments behave in supramolecular complexes, up to the complete modeling of pigment organelles. We also discuss the main limitations of quantum chemistry, emphasizing the need for carrying experimental work with identical vigor. We finally suggest that taking into account the ecology of pigments (i.e., how they interact with these various other cellular components and at higher organizational levels) will lead to a greater understanding of how and why animals are vividly and variably colored, two fundamental questions in organismal biology.

Tough Multimaterial Interfaces through Wavelength-Selective 3D Printing.

Strong and well-engineered interfaces between dissimilar materials are a hallmark of natural systems but have proven difficult to emulate in synthetic materials, where interfaces often act as points of failure. In this work, curing reactions that are triggered by exposure to different wavelengths of visible light are used to produce multimaterial objects with tough, well-defined interfaces between chemically distinct domains. Longer-wavelength (green) light selectively initiates acrylate-based radical polymerization, while shorter-wavelength (blue) light results in the simultaneous formation of epoxy and acrylate networks through orthogonal cationic and radical processes. The improved mechanical strength of these interfaces is hypothesized to arise from a continuous acrylate network that bridges domains. Using printed test structures, interfaces were characterized through spatial resolution of their chemical composition, localized mechanical properties, and bulk fracture strength. This wavelength-selective photocuring of interpenetrating polymer networks is a promising strategy for increasing the mechanical performance of 3D-printed objects and expanding light-based additive manufacturing technologies.

Light scattering from colloidal aggregates on a hierarchy of length scales.

Disordered dielectrics with structural correlations on length scales comparable to visible light wavelengths exhibit interesting optical properties. Such materials exist in nature, leading to beautiful structural non-iridescent color, and they are also increasingly used as building blocks for optical materials and coatings. In this article, we explore the angular resolved single-scattering properties of micron-sized, disordered colloidal assemblies. The aggregates act as structurally colored supraparticles or as building blocks for macroscopic photonic glasses. We obtain first experimental data for the differential scattering and transport cross-section. Based on existing macroscopic models, we develop a theoretical framework to describe the scattering from densely packed colloidal assemblies on a hierarchy of length scales.

Bi/BiVO4/NiFe-LDH heterostructures with enhanced photoelectrochemical performance for streptomycin detection

Streptomycin (STR) plays an essential role in bacterial infection treatments. Selectivity and sensitivity of photoelectrochemical (PEC) sensors are the two most important parameters, which can be measured using the photosensitivity of its active material. We prepared a novel PEC sensor to detect STR using Bi/BiVO4/LDH (layered double hydroxides) heterostructures as an active material, which is photoactive in the visible light wavelength range. The simultaneous presence of LDH and Bi/BiVO4 enhanced the material photocurrent response, which was linear to the STR concentrations in the 0.01–500 nmol/L range. The STR detection limit by this sensor was 0.0042 nmol/L. Our novel PEC-based sensing strategy includes using an ultra-sensitive and highly selective sensor for STR detection. Additionally, the two-pot synthesis of Bi/BiVO4/LDH developed in this work is environmentally friendly.

Structure and optical properties of nanocomposites based on polystyrene (PS) and calcium titanate (CaTiO3) perovskite nanoparticles

Polystyrene (PS) thin films containing 4% and 8% calcium titanate (CaTiO3) perovskite nanofiller were prepared by film casting techniques. The influence of CaTiO3 loading on the structure and optical characteristic of PS were studied by using X-ray diffraction and UV-absorption spectroscopy. The XRD analysis showed the addition of CaTiO3 into PS enhanced the formation of crystal structure and resulted in the formation of nano-crystal with a smaller diameter. The optical characterizations showed that the addition of CaTiO3 reduced the transmission and increased the reflection of PS films for UV and visible wavelength of the incident light. Absorption of pure PS films was limited to less than 270 nm, while the absorption of PS/CaTiO3 composites film covered the whole UV -range. The values of the optical energy gap were calculated by using Tauc equation. It was found that the addition of 8% CaTiO3 decreased the values of optical energy gaps from 4.42 eV to 4.26 eV. This is suggested the formation of extra energy levels in the bandgap tails, which aided the transition of electrons from the valence band to these new energy levels in the conduction band.

Gradual transmittance controllable device via ion intercalation for spatial light modulators

To realize a hologram that is an effective method for implementing three-dimensional display, a novel spatial light modulator (SLM) that can generate the hologram by light interference and diffraction was developed based on transmittance changes. For a high-resolution hologram, pixel size of the SLM needs to be scaled down to visible light wavelength (380∼780 nm). However, conventional liquid crystal or micro-mirror-based SLM has a limitation in scaling down; few micrometers sized unit parts are required based on its operation mechanism. Herein, an ion intercalation-based SLM utilizing nano-scale ions as the unit part was investigated. Consequently, basic operations of the SLM (light interference and diffraction) are achieved based on the gradual transmittance changes, which demonstrates the feasibility of ion intercalation-based SLM.

539 If Seeing Was Believing - A Retrospective Analysis of Potential Reduced Treatment Delays with a Novel Burn Wound Assessment Device.

Abstract Introduction Burn care (BC) remains a highly specialized and resource intensive specialty with only 2% of hospitals featuring a burn center and less than 1% of graduating general surgery and plastic surgery residents pursing a burn fellowship each year. Access to specialized care is further complicated by burn wound assessment (BWA) which is commonly performed visually without adjunctive devices. To help clinicians make more accurate assessments and potentially reduce delays in transfer or treatment, a new non-invasive imaging device for BWA is being developed using visible and non-visible wavelengths of light with machine learning algorithms. Our goal was to assess the potential reduced treatment delay (RTD) and associated financial savings by implementing such a device using our burn center’s historical data. Methods The study was an IRB-approved, retrospective review of admissions from 07/01/2018 through 06/30/2019. Inclusion criteria: thermal, chemical, contact, or electrical mechanism of injury, >15 years of age requiring excision, and length of stay >72 hours. Inclusion data included: presence/absence of concomitant trauma, day of surgery, day of admission, day of electronic order entry for case request, and length of stay per percent total body surface area (LOS%TBSA). RTD was defined starting >48 hours after injury daily until electronic order entry for surgical case request. Reduced costs were calculated per day from prior studies ranging $3,000 to $5,100/day. Results A total of 109 patients were included. 29 patients had case requests placed within 48 hours of admission. Of the remaining 80 patients, a potential of 398 days would have been saved had a novel BWA adjunctive imaging devices aided surgeon to requests earlier surgical intervention. Overall savings from reduced length of stay range from $1,194,000 to $2,029,800 dollars. Conclusions Our study demonstrates that should a BWA technology with accuracy 48 hours after injury be developed, even burn centers with 24-hour access to operating rooms can reduce treatment delays. The study does not look at additional cost savings offered by reduced emergent transfers or admissions which offer additional intrigue and promise.

In Situ Visualizing Oxidase-Mimicking Activity of Single MnOOH Nanotubes with Mie Scattering-Based Absorption Microscopy.

Imaging the catalytic activity at the single-particle level can greatly promote the screening and rational design of highly efficient nanozymes, but conventional techniques are based on ensemble analysis. Here, we present a new absorption microscopy for in situ visualizing oxidase-mimicking activity of single MnOOH nanotubes. The particle with a size more than 700 nm roughly equally scatters all wavelengths of visible light via Mie scattering, and the scattering light is collected by dark-field optical microscopy. When the particles absorb a single color of the scattering light, each individual nanoparticle shows its complementary color, enabling a form of absorption microscopy that we name Mie scattering-based absorption microscopy. We find that MnOOH nanotubes can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to generate polyTMB nanowires at their tips. There are multiple active sites on the surface of the individual nanotube, and the nanozyme activity shows a large heterogeneity as well as pH-dependent characteristic.

Fluorescent nanotechnology for in vivo imaging.

Fluorescent imaging in living animals gives an intuitive picture of the dynamic processes in the complex environment within a living being. However, animal tissues present a substantial barrier and are opaque to most wavelengths of visible light. Fluorescent nanoparticles (NPs) with new photophysical characteristics have shown excellent performance for in vivo imaging. Hence, fluorescent NPs have been widely studied and applied for the detection of molecular and biological processes in living animals. In addition, developments in the area of nanotechnology have allowed materials to be used in intact animals for disease detection, diagnosis, drug delivery, and treatment. This review provides information on the different types of fluorescent particles based on nanotechnology, describing their unique individual properties and applications for detecting vital processes in vivo. The development and application of new fluorescent NPs will provide opportunities for in vivo imaging with better penetration, sensitivity, and resolution. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging.

EVALUATION OF REFLECTANCE FOR BUILDING MATERIALS CLASSIFICATION WITH TERRESTRIAL LASER SCANNER RADIATION

The main purpose of this work is the evaluation of the potential of Terrestrial Laser Scanning (TLS) technology to perform a reflectance analysis of scanned objects. A laser beam, having a coherent beam in the field of visible light (wavelength between 532nm and 680 nm), can lead to optical diffraction phenomena that allow a correlation between the degree of crystallinity of solids (in particular dispersed crystalline materials) and its reflectivity. Different materials with known crystallinity values have been examined and the diffraction value has been analysed for two types of lasers, one pulsed and the other phase measurement, with two different acquisition conditions (nadiral and oblique position). The results demonstrated the correlation by verifying that the incident laser light beam is more refracted by materials with a higher degree of crystallinity than less crystalline or amorphous materials.

Study of light wavelength on the oxidative stability of Jatropha biodiesel

The oxidative stability of Jatropha biodiesel after exposure to different wavelengths of visible light was studied and kinetic analysis of the oxidation process was carried out. The results showed that the induction period of Jatropha biodiesel was 5.12 h and visible light at different wavelengths affected the oxidation of biodiesel differently. Effect of oxidation was the strongest in the purple, where the induction period was reduced to 2.65 h. The red had the weakest effect on biodiesel oxidation, and the induction period was reduced to 4.61 h. Acid value detection, component analysis and UV characterization of biodiesel oxidized by visible light at different wavelengths. The results showed that with the decrease of light wavelength, the acid value of the biodiesel increased from 0.2577 mg KOH/g to 0.3438 mg KOH/g and the content of methyl linoleate containing two carbon–carbon double bonds decreases. UV characterization results showed that the absorption peak absorbance of conjugated double bond of Jatropha biodiesel oxidized by purple light was 5.282, while the absorption peak absorbance of conjugated double bond of Jatropha biodiesel oxidized by red light was only 2.877, and purple light was helpful to stimulate the generation of conjugate double bond. The kinetic analysis results showed that the different wavelengths had different rates of biodiesel degradation. Purple light has the fastest oxidation rate. The oxidation rate constant k1 was 0.06011, the reaction order was n = 1, and the minimum activation energy of the oxidation reaction process was 19.79 kJ·mol−1.

Series Photothermoelectric Coupling Between Two Composite Materials for a Freely Attachable Broadband Imaging Sheet

As flexible wearable sensors and imagers are receiving attention from diverse social sectors, the freely attachable photothermoelectric (PTE) conversion technique should be evaluated to develop a highly usable safety sensor network. Although carbon nanotube (CNT)‐related materials should be effective, the key parameters/structures that maximize PTE conversion have not been clarified, thus hindering optimum device design and practical use. Herein, the flexible, sensitive broadband photodetection operation based on a coupling configuration between the CNT film photo/heat/electron channel and metal electrode is evaluated. Experimental PTE measurements and steady‐state thermal distribution simulations reveal that a series coupling of a p‐type CNT film channel and a highly negative Seebeck coefficient counter metal electrode facilitate superior photodetection performances than those of a parallel coupling configuration. Furthermore, subsequent device designs provide sensitive broadband photodetection from the millimeter‐wave to visible light wavelength regions with a minimum noise equivalent power of 5 pWHz−1/2 in an uncooled nonvacuum condition. Simultaneously, the mechanical flexibility of the proposed photodetector allows for its use in freely attachable sheet imager applications on curvilinear objects, and the nondestructive 3D photomonitoring of a defective intricately bent sample is demonstrated.

Plasma Treatment as a Promising Environmentally Benign Approach for Synthesis of Valuable Multi-gas Doped Nano-TiO2 -P25: An Efficient Way to Boost the Photocatalytic Performance under Visible Light Illumination.

An ingenious prospect has been established to synthesize a wide range of non-metal-doped TiO2 -P25 by plasma technique. Different atmospheres (Air, O2 , N2 , Ar and CO2 ) have been embedded on the surface of TiO2 -P25 by plasma treating as an effective alternative to wet chemical pretreatment processes. This approach is clean beyond recognition by employing pure gases as well as no need to poison precursors or organic solvents without producing waste stream, which surprisingly can meet green chemistry purposes. More specifically, plasma has been a contributing factor in the narrowing band gap energies of doped photocatalysts in comparison with pure TiO2 -P25. Synthesized photocatalysts gained enormous benefit from the plasma treatment in the selective oxidation of benzyl alcohols to associating aldehydes under blue LED illumination with excellent yields, which dramatically decreased the time reaction to many folds. Additionally, benzaldehyde formation under influence of various wavelengths of visible light, including blue photons (λmax = 460 nm), green photons (λmax = 510 nm) and red photons (λmax = 630 nm) was compared to assess the effect of plasma treating on photoactivity of nano-TiO2 -P25. Furthermore, as-prepared photocatalysts were investigated by diverse characterization techniques.

Tunable orange, yellow and white emission of Pr3+-doped tungsten gadolinium borate glasses

Pr3+ doped WO3-Gd2O3-B2O3 glasses were prepared by the melt quenching technique to study in the luminescence under different excitation. X-ray diffraction (XRD) pattern represents the dominant vitreous disordered structure. The glass with 2.0 mol% of Pr2O3 possess a massive density at 6.15 g/cm3. The luminescence spectra of Pr3+ doped glasses were recorded under the various excitation wavelengths of visible light and under the electron excitation. The streak camera was used to measure decay time. The developed glasses show tunable luminescence property, orange under 435 and 447 nm excitation, yellow under 471 and 484 nm excitation and white under the electron excitation. The photo- and catodoluminescence decay times of glasses are comparable. The optimal concentration of Pr2O3 in the glass is 0.1 mol% that performed the highest emission intensity. This glass can be considered as a new low-cost alternative for the tunable light source and the electron detection material.

Charge Transfer in 4-Mercaptobenzoic Acid-Stabilized Au Nanorod@Cu2O Nanostructures: Implications for Photocatalysis and Photoelectric Devices

Nanoscale materials have an irreplaceable advantage in solar energy utilization because of their perfect match with visible light wavelength on the length scale. Charge transfer (CT) between a metal nanoparticle and contacted nanoscale semiconductor plays a significant role in photoinduced energy transfer. Here, we fabricated a new complex, a gold nanorod-4-mercaptobenzoic acid@Cu2O (Au NR-MBA@Cu2O) core–shell nanostructure, and used surface-enhanced Raman scattering (SERS) spectroscopy of the interlayer MBA molecules to investigate the CT process occurring between the Au NRs and Cu2O. In our system, different surface plasmon absorption bands were adjusted by tuning the thicknesses of the Cu2O shells on the Au NR core to explore the influence of plasmon absorption at different incident Raman laser lines. By analyzing the SERS spectra, the degree of CT was calculated, and the consequences can be fully explained by photoexcitation across interface electron transfer and plasmon-induced interfacial charge transfer transition at laser excitation wavelengths of 633 and 785 nm. This experiment introduced a simple, effective, and intuitive approach to observe the CT process in metal semiconductors by SERS. The results of our study will improve in photocatalytic efficiency and photoelectric devices.

Preparation of cuprous iodide transparent thermoelectric materials by SILAR method

Thermoelectric generator can obtain electric energy from waste heat, which is one of the best ways to recycle the energy from waste heat. At present, most thermoelectric materials tend to be opaque, so the preparation of transparent thermoelectric materials is one of the research directions of thermoelectric materials. In this work, p-type transparent CuI films were prepared by successive ionic layer adsorption and reaction (SILAR) method. The crystalline structure of the film was determined to be γ-CuI by X-ray diffraction. The surface morphology of the film analyzed by scanning electron microscope was flat. In the wavelength of visible light, the average transmittance of CuI film is 60-70%. The energy band of the prepared CuI film is calculated by the formula to be about 3.04 eV. The results show that the CuI film prepared by the SILAR method has excellent optical transparency.

UVC Light Simulation for Room Disinfection System

Viruses are minuscule parasites that have gained notoriety for causing diseases. However, these harmful pathogens can be inactivated using Ultraviolet-C (UVC) radiation that has a wavelength between 200 – 280 nm. The wavelengths of the UVC are responsible for germicidal effect as the proteins (e.g. RNA and DNA) absorb the maximum radiation in these wavelengths and damage the DNA of the viruses so that they cannot replicate. This project aimed to simulate the UVC light intensity in different room layouts to guide the evaluation of the effectiveness of surface disinfection system which consists of UVC lights. Besides determining the quantity and the installation layout of the UVC lights, the project also aimed to help visualisation of the coverage of UVC radiation and highlight any under-exposed area for optimum room disinfection using a simulation software. DIALux Evo 9.1 was used to simulate the light intensity in different room and lighting layouts. As the software only calculates normal visible light (wavelength 380 – 700 nm) intensity in the unit of Lux, a correlation between Lux and UVC dosage (mJ/cm2) must be established first. A minimum UVC dosage of 40 mJ/cm2 is required to achieve complete surface disinfection of microorganisms. The simulation was able to visualize the coverage of UVC radiation and to determine the optimum placement of UVC lights to ensure sufficient UVC dosage is delivered to every critical surface. The outcome of this project can help to guide the design of UVC room disinfection system especially in hospital wards setting to optimise room disinfection and reducing the risk of infection.

Determination of ammonium in natural water using a quinoline-based o-dialdehyde fluorescent reagent with visible excitation wavelength.

In this paper, a novel and stable fluorescent reagent, quinoline-2,3-dicarbaldehyde (QDA), is synthesized as a probe to detect ammonium in natural water. Ammonium reacts with QDA in the presence of SO32- and Ca2+ to form a fluorescence product, which has maximum excitation and emission wavelengths at 429 nm and 518 nm. The concentration of reagents, the reaction temperature, the reaction time, and the pH in the final solution are investigated and optimized. The interferences of typical organic nitrogen and inorganic compounds are evaluated, and results prove that most volatile amines have little or negligible effect. Under the optimized conditions, this method provides a limit of detection of 0.065 μmol L-1, a calibration range of 0.216-9 μmol L-1, and reproducibility (with a relative standard deviation) of 1.9% for 1.5 μmol L-1 ammonium. For water sample analysis, the proposed method provides comparable results to those of the conventional o-phthalaldehyde method but has longer reagent stability (42 days).

Effect of Yb/Co co-dopants on surface chemical bonding states of BiFeO3 nanoparticles with promising photocatalytic performance in dye degradation

In this work the nanocrystalline particles of BiFO3 co-doped with ytterbium and cobalt Bi1-xYbxFe1-xCoxO3 (x = 0.0, 0.02, 0.04, 0.06, 0.08) were synthesized via sol-gel method. The phase purity and crystallinity of the synthesized particles were examined by X-ray diffraction (XRD) technique. The values of the diffraction peaks match precisely with the standard data (JCPDS card no.-71-2494). XRD data also ensures the formation of rhombohedral symmetry of R3C space group. Raman spectra over the frequency range of 800–1600 cm−1 have been systematically investigated with different excitation wavelengths. For determining vibrational modes of the doped nanoparticles, Raman scattering spectra at excitation wavelengths λ = 532 nm was recorded. FESEM images reveal the fact that, x = 0.02 doping significantly reduces the grain size resulting high surface area for active sites.X-ray photoelectron spectroscopy (XPS) was also carried out to estimate the compositions and the valence states of elements in Bi1-xYbxCoxFe1-xO3 (x = 0.04, and 0.06) nanoparticles. The substitution of Yb3+ and Co2+ ions in BFO nanocrystalline samples, improves the magnetic and photocatalytic properties. The entire range of visible light wavelength absorption is observed in all the synthesized nanoparticles and were analysed by UV–Visible absorption spectroscopy. The energy band gap was found to be ~2.30 eV for pure BFO, which get altered by Yb3+ and Co2+ substitution and found to be ~1.88 eV in case of Bi0.94Yb0.06Fe0.94Co0.06O3 nanoparticle. The photocatalytic properties get enhanced with the substitution of Yb3+and Co2+ in BFO, that may be due to change in energy band gap and formation of trapping sight, which results into increase in the number of electron hole pair and hence improve the photocatalytic properties.

Bio-inspired structural colors and their applications.

Structural colors, generated by the interaction of interference, diffraction, and scattering between incident light and periodic nanostructured surfaces with features of the same scale with incident visible light wavelengths, have recently attracted intense interest in a wide range of research fields, due to their advantages such as various brilliant colors, long-term stability and environmental friendliness, low energy consumption, and mysterious biological functions. Tremendous effort has been made to design structural colors and considerable progress has been achieved in the past few decades. However, there are still significant challenges and obstacles, such as durability, portability, compatibility, recyclability, mass production of structural-color materials, etc., that need to be solved by rational structural design and novel manufacturing strategies. In this review, we summarize the recent progress of bio-inspired structural colors and their applications. First, we introduce several typical natural structural colors displayed by living organisms from fundamental optical phenomena, including interference, diffraction grating, scattering, photonic crystals effects, the combination of different phenomena, etc. Subsequently, we review recent progress in bio-inspired artificial structural colors generated from advanced micro/nanoscale manufacturing strategies to relevant biomimetic approaches, including self-assembly, template methods, phase conversion, magnetron sputtering, atomic layer deposition, etc. Besides, we also present the current and potential applications of structural colors in various fields, such as displays, anti-counterfeiting, wearable electronics, stealth, printing, etc. Finally, we discuss the challenges and future development directions of structural colors, aiming to push forward the research and applications of structural-color materials.