Color Output Research Articles

Lanthanide‐Based Molecular Cluster‐Aggregates: Optical Barcoding and White‐Light Emission with Nanosized {Ln20} Compounds

AbstractCounterfeit goods represent a major problem to companies, governments, and customers, affecting the global economy. In order to protect the authenticity of products and documents, optical anti‐counterfeit technologies have widely been employed via the use of discrete molecular species, extended metal–organic frameworks (MOFs), and nanoparticles. Herein, for the first time we demonstrate the potential use of molecular cluster‐aggregates (MCA) as optical barcodes via composition and energy transfer control. The tuneable optical properties for the [Ln20(chp)30(CO3)12(NO3)6(H2O)6], where chp−=deprotonated 6‐chloro‐2‐pyridinol, allow the fine control of the emission colour output, resulting in high‐security level optical labelling with a precise read‐out. Moreover, a unique tri‐doped composition of GdIII, TbIII, and EuIII led to MCAs with white‐light emission. The presented methodology is a unique approach to probe the effect of composition control on the luminescent properties of nanosized molecular material.

Modulating electron population pathways for time-dependent dynamic multicolor displays.

Multicolor luminescent nanoparticles (NPs) show several potential emerging applications. In this work, we provide a new route that integrates the afterglow and upconversion (UC) that originate in a single activator to achieve color variations without the modulation of any other parameters. The Er3+ ions in Na3HfF7:Yb/Er NPs exhibit bright green afterglow upon X-ray irradiation and single-band red UC under 980 nm laser excitation, which are attributed to the significantly different electron population pathways. The UC intensity is stable and the afterglow decreases gradually over time, thus the output color is clearly changed from green to red naturally via illuminating the pre-X-ray-irradiated NPs with a 980 nm laser. Furthermore, the fine emission profiles of Er3+, Ho3+ and Tm3+ are achieved upon X-ray irradiation. Our results develop a new approach for time-dependent dynamic color displays and a simple route to revealing the electronic fine structures of lanthanide activators at room temperature.

A novel vertical flow assay for point of care measurement of iron from whole blood.

Disorders in iron metabolism are endemic globally, affecting more than several hundred million individuals and often resulting in increased rates of mortality or general deterioration of quality of life. To both prevent and monitor treatment of iron related disorders, we present a point of care medical device which leverages a simple smartphone camera to measure total iron concentration from a finger-prick sample. The system consists of a smartphone and an in-house developed app, a 3D printed sensing chamber and a vertical flow membrane-based sensor strip designed to accommodate 50 μl of whole blood, filter out the cellular components and carry out a colorimetric chelation reaction producing a colour change which is detected by our smartphone device. The app's accuracy and precision were assessed via comparison of the mobile app's RGB output to a reference imaging software, ImageJ for the same colorimetric sensing strip. Correlation plots resulted in slopes of 0.99 and coefficient of determination (R2 = 0.99). The device was determined to have a signal to noise ratio >40 and a mean bias of 2% which both indicate high analytical accuracy and precision (in terms of RGB measurement). The smartphone device's iron concentration readout was then studied using an extensively validated laboratory developed test (LDT) for iron detection, which is an optimized spectrophotometry-based technique (this is considered the gold standard for iron quantification among LDTs). In comparison of the smartphone-based technique with the gold standard LDT, a calibration slope of 0.0004 au μg-1 dL-1, a correlation plot with slope of 1.09 and coefficient of determination (R2) of 0.96 and a mean bias of 5.3%, our device can accurately measure iron levels in blood. With detection times of five minutes, fingerpick sample and sensor cost less than 10 cents, the device shows great promise in being developed as the first ever commercial device for iron quantification in blood.

Afterglow Carbon Dots: From Fundamentals to Applications.

The ability of carbon dots (CDs) to emit afterglow emission in addition to fluorescence in response to UV-to-visible excitation allows them to be a new class of luminescent materials. When compared with traditional organic or inorganic afterglow materials, CDs have a set of advantages, including small size, ease of synthesis, and absence of highly toxic metal ions. In addition, high dependence of their afterglow color output on temperature, excitation wavelength, and aggregation degrees adds remarkable flexibility in the creation of multimode luminescence of CDs without the need for changing their intrinsic attributes. These characteristics make CDs particularly attractive in the fields of sensing, anticounterfeiting, and data encryption. In this review, we first describe the general attributes of afterglow CDs and their fundamental afterglow mechanism. We then highlight recent strategic advances in the generation or activation of the afterglow luminescence of CDs. Considerable emphasis is placed on the summarization of their emergent afterglow properties in response to external stimulation. We further highlight the emerging applications of afterglow CDs on the basis of their unique optical features and present the key challenges needed to be addressed before the realization of their full practical utility.

Adversarial Edge-Aware Image Colorization With Semantic Segmentation

It has become a trend in recent years to use deep neural networks for colorization. However, previous methods often encounter problems with edge color leakage and difficulties in obtaining a plausible color output from the Euclidean distance. To solve these problems, we propose a new adversarial edge-aware image colorization method with multitask output combined with semantic segmentation. The system uses a generator with a deep semantic fusion structure to infer semantic clues in a given grayscale image under chroma conditions and learns colorization by simultaneously predicting color information and semantic information. In addition, we also use a specific color difference loss with characteristics of human visual observation that is combined with semantic segmentation loss and adversarial loss for training. The experimental results show that our method is superior to existing methods in terms of different quality metrics and achieves good results in image colorization.

Shade Matching of CAD/CAM Lithium Silicate Ceramics Veneered on Newly Introduced Foundation Material.

Statement of the problem: The emergence of Polyetheretherketone (PEEK) in prosthodontics and its use as a foundation for ceramic veenering restorations demand reassessment of shade match of final restoration. Purpose: This study aimed to investigate the use of different foundation materials on the color output of two CAD/CAM lithium silicate ceramics. Material and Methods: Rectangular plate specimens (60 sample) were prepared from CAD/ CAM generated all-ceramic materials of shade A2; IPS e.max (EM) CAD and Vita suprinity blocks (ZLS). A reflectance spectrophotometer used to measure the colour difference of ceramic samples before and after bonding to different foundation specimens; Zirconia (ZR), resin composite (RC), and PEEK; all of shade A2. The parameter of colour were measured via CIE L*a*b* (Commission Internationale de L’Eclairage) color system. Statistical analysis of data were done using two way ANOVA and the Tukey HSD test (α=0.05). Results:ANOVA revealed that ΔE values influenced significantly (P<.05) by the composition of ceramic material and different foundation materials used. However; the interaction was almost not statistically significant between the variables (p=.294). In comparison to ZR and RC assemblies, the foundation material; PEEK, revealed comparable color parameters when assembled with each of the tested veneering material. Conclusions: Zirconia reinforcement of CAD / CAM lithium silicate glass-ceramics decrease the impact of color variations on the various foundation materials used. The level of color acceptance varies between the ceramic and foundation materials tested. Compared to other widely used foundation materials (ZR and RC); PEEK displayed no different tendencies in color properties.

Eu3+/Eu2+/Tb3+ co-activated single-phase Gd2O2S: A high-performance white light emitting phosphor for light emitting diode

In this work, we report Eu3+/Tb3+/Eu2+ co-activated Gd2O2 S as novel phosphor materials that can be effectively applied in the white-light emitting diode based on a near-UV chip with sensational performances. The luminescent properties and energy transfer mechanism have been thoroughly investigated. The as-prepared europium/terbium co-doped Gd2O2 S phosphors exhibit strong fluorescence with tunable color output under UV-vis light excitation. Furthermore, a high response to ultraviolet illumination of 398 nm wavelength was observed in the excitation spectra, indicating an excellent match with a light-emitting-diode chip in the dominant emissions. It is found that a tricolor (blue, green and red) emission band which results in a white light emission can be acquired when Eu3+, Eu2+ and Tb3+ ions are all co-doped into the single phase Gd2O2S, and an optimum ion doping level (10 at.% Eu and 0.7 at.% Tb) can effectively emit nearly pure white color photoluminescence with lifetime effectively tuned from 0.55 ms to 1.10 ms. The CIE (Commission International de I'Eclairage 1931 chromaticity) is X = 0.3507, Y = 0.3029. It is therefore expected that the newly found phosphor material with high-performance properties possess great potentials for the future advanced white LED applications.

Artificial Intelligence and Robotics in Regional Anaesthesia: Do they have a role?

Artificial Intelligence and Robotics in Regional Anaesthesia: Do they have a role?

Stomach 3D Reconstruction Using Virtual Chromoendoscopic Images.

Gastric endoscopy is a golden standard in the clinical process that enables medical practitioners to diagnose various lesions inside a patient’s stomach. If a lesion is found, a success in identifying the location of the found lesion relative to the global view of the stomach will lead to better decision making for the next clinical treatment. Our previous research showed that the lesion localization could be achieved by reconstructing the whole stomach shape from chromoendoscopic indigo carmine (IC) dye-sprayed images using a structure-from-motion (SfM) pipeline. However, spraying the IC dye to the whole stomach requires additional time, which is not desirable for both patients and practitioners. Our objective is to propose an alternative way to achieve whole stomach 3D reconstruction without the need of the IC dye. We generate virtual IC-sprayed (VIC) images based on image-to-image style translation trained on unpaired real no-IC and IC-sprayed images, where we have investigated the effect of input and output color channel selection for generating the VIC images. We validate our reconstruction results by comparing them with the results using real IC-sprayed images and confirm that the obtained stomach 3D structures are comparable to each other. We also propose a local reconstruction technique to obtain a more detailed surface and texture around an interesting region. The proposed method achieves the whole stomach reconstruction without the need of real IC dye using SfM. We have found that translating no-IC green-channel images to IC-sprayed red-channel images gives the best SfM reconstruction result. Clinical impact We offer a method of the frame localization and local 3D reconstruction of a found gastric lesion using standard endoscopy images, leading to better clinical decision.

Dual‐Color Flexible Metasurfaces with Polarization‐Tunable Plasmons in Gold Nanorod Arrays

AbstractOptical metasurfaces have attracted growing attention in plasmonic structural color in recent years due to their supreme performance in display and imaging technologies. However, real‐life applications of optical metasurfaces so far are often hindered by their complex, expensive, and time‐consuming nanofabrication methods, as well as sophisticated optical measurement systems. Herein, a flexible metasurface filter, based on periodic gold nanorods, capable of changing the output color by simple rotation of a linear polarizer is proposed and demonstrated. This phenomenon is enabled by switching of resonance plasmons in the gold nanorods with the polarization of incident light. Subsequent rotation of the input polarizer leads to an output of two distinct colors and their combinations. Moreover, metasurfaces consisting of Au nanorods with different orientations are integrated into a single flexible substrate. Information can be therefore encoded into the orientations of Au nanorods and readily decoded with the color of the metasurface under polarized illumination of white light‐emitting diode without complex optical components.

Reflectin needs its intensity amplifier: Realizing the potential of tunable structural biophotonics

Underwater camouflage and communication in a family of recently evolved squids are controlled, in part, by the reflectin proteins, which regulate dynamic changes in the color and intensity of light reflected from intracellular Bragg reflectors and Mie scatterers. The reflectins act as a signal transducer, precisely tuning the dimensions and refractive index of the membrane-bounded structural reflectors containing them to an extent exactly proportional to neuronal signaling. This calibration between the activating signal and the output color and intensity of reflectance is governed by the physics of the liquid state of reflectin assemblies, which osmotically fine-tune the dimensions and refractive index of the membrane-bounded structural reflectors containing them. While thin-film or genetically engineered assemblies of reflectin deliver changes in the colors of reflection approximating those of the biological system (as do other proteins and polymers), none has delivered the signal-activated increase in the intensity of reflectance characteristic of the native system. The membrane envelopes (Bragg reflector lamellae and Mie-scattering vesicles) containing the reflectins apparently serve as amplifiers, functionally “impedance matched” to the range of tunable sizes of the reflectin assemblies; reflectin films or assemblies lacking such an amplifier fail to deliver signal-activated increases in reflectance intensity.

Nonlinear vibration and geometric optimization of nanocomposite multilayer organic solar cell under wind loading

This paper presents an analytical approach on the nonlinear vibration of nanocomposite multilayer organic solar cell (NMOSC) subjected to the combination of wind load and uniform temperature change. The NMOSC comprises of five layers, which are made of Al, P3HT:PCBM, PEDOT:PSS, Graphene and Glass. Compared to common models of the NMOSC, ITO is replaced by graphene to control the output colors of NMOSC. The nonlinear motion equations and the compatibility equation are deriving by taking into account the effect of viscous damping, von Karman nonlinearity terms, elastic foundations and initial imperfection. The formula of the wind load is improved for consideration in the general case that the direction of the wind load is not just perpendicular to the structure. Four edges of the NMOSC are assumed to be simply supported and immovable in the transverse plane. The Galerkin and Runge – Kutta methods are applied to obtain the dynamic response and the natural frequency of the NMOSC. Four optimization algorithms (Bees Algorithm, Basic differential evolution algorithm, enhanced colliding bodies optimization algorithm, social group optimization algorithm) are used to determine the maximum value of natural frequency of the NMOCS, which depends on nine variables including the geometrical parameters, elastic foundations stiffness and temperature increment. In the numerical results, the effects of elastic foundations, initial imperfection, viscous damping ratio, temperature increment, wind load and the length to width ratio on the dynamic response and natural frequency are considered in details. The maximum values of the natural frequency of the NMOSC with four algorithms are obtained and compared. The results show that the optimal value obtained by four algorithms is close to each other. However, the calculation time with enhanced colliding bodies optimization algorithm is the fastest and with Bees Algorithm is the longest of all.

Morphology Related Defectiveness in ZnO Luminescence: From Bulk to Nano-Size.

This study addresses the relationship between material morphology (size, growth parameters and interfaces) and optical emissions in ZnO through an experimental approach, including the effect of different material dimensions from bulk to nano-size, and different excitations, from optical sources to ionizing radiation. Silica supported ZnO nanoparticles and ligand capped ZnO nanoparticles are synthesized through a sol–gel process and hot injection method, respectively. Their optical properties are investigated by radioluminescence, steady-state and time-resolved photoluminescence, and compared to those of commercial micrometric powders and of a bulk single crystal. The Gaussian spectral reconstruction of all emission spectra highlights the occurrence of the same emission bands for all samples, comprising one ultraviolet excitonic peak and four visible defect-related components, whose relative intensities and time dynamics vary with the material parameters and the measurement conditions. The results demonstrate that a wide range of color outputs can be obtained by tuning synthesis conditions and size of pure ZnO nanoparticles, with favorable consequences for the engineering of optical devices based on this material.

Energy Manipulation in Lanthanide-Doped Core-Shell Nanoparticles for Tunable Dual-Mode Luminescence toward Advanced Anti-Counterfeiting.

Developing advanced luminescent materials and techniques is of significant importance for anti-counterfeiting applications, and remains a huge challenge. In this work, a new and efficient approach for achieving efficient dual-mode luminescence with tunable color outputs via Gd3+ -mediated interfacial energy transfer, Ce3+ -assisted cross-relaxation, and core-shell nanostructuring strategy is reported. The introduction of Ce3+ into the inner core not only serves the regulation of upconversion emission, but also facilitates the ultraviolet photon harvesting and subsequent energy transfer to downshifting (DS) activators in the outer shell layer. Furthermore, the construction of the core@shell nanoarchitecture enables the spatial separation of upconverting activators and DS centers, which greatly suppresses their adverse cross-relaxation processes. Consequently, efficient and multicolor-tunable dual-mode emissions can be simultaneously observed in the pre-designed NaGdF4 :Yb/Ho/Ce@NaYF4 :X (X = Eu, Tb, Sm, Dy) core-shell nanostructures under 254 nm ultraviolet light and 980 nm laser excitation. The proof-of-concept experiment demonstrates that 2D-encoded patterns based on dual-mode emitting nanomaterials are very promising for anti-counterfeiting applications. It is believed that this preliminary study will advance the development of the fluorescent materials for potential applications in anti-counterfeiting and optical multiplexing.

Power density dependent upconversion properties of NaYbF4: Er3+@NaYbF4: Tm3+@NaYF4 nanoparticles and their application in white-light emission LED

White light sources play a vital role in our daily lives, which were usually generated by optimizing the proportions of individual emitters with different colors. Benefiting from the abundant energy levels of rare earth ions (Re3+), Re3+ doped upconversion nanoparticles (UCNPs) with multicolor luminescence output in one fixed structure have attracted broad attention. Here, we constructed a NaYbF4: Er3+@NaYbF4: Tm3+@NaYF4 core-shell-shell structure with Er3+ and Tm3+ in different layers to avoid the cross-relaxation. In the structure, red and green emissions were originated from Er3+, and blue emission was generated by Tm3+ through the upconversion process. The simultaneous red, green and blue emissions in the designed structure made it possible to realize white light emission. More importantly, the NaYbF4 host leads to three photons upconversion pathway and result in tunable color output under moderate varying power density. The results showed that warm white color was achieved at the excitation power of 20.9 W/cm2, meanwhile, tunable output colors were also realized by changing the external excited power density. Finally, the high luminescence intensity of NaYbF4: Er3+@NaYbF4: Tm3+@NaYF4 makes it possible to be excited by a near infrared-light emitting diode (NIR-LED), and a white emission LED was prepared by encapsulating the prepared UCNPs on a NIR chip.

Simultaneous Determination of l-Phenylalanine, Phenylethylamine, and Phenylacetic Acid Using Three-Color Whole-Cell Biosensors within a Microchannel Device.

The neurotransmitter phenylethylamine (PEA) is highly susceptible to oxidation to produce phenylacetic acid (PA). The fact that PEA and PA are both metabolites of phenylalanine (Phe) in humans makes them important indicators in the diagnosis of phenylketonuria. In this work, three-color whole-cell biosensors were developed to simultaneously detect these analytes (Phe, PEA, and PA). The tyrosine-responsive promoter was used to control the production of green fluorescent protein signals in response to Phe levels. The FeaR regulon was first used to indicate the presence of PEA, whereas the Paa regulon was used for the detection of PA. The combination of three sensor strains together made it possible to semiquantify the three analytes according to unique color outputs without cross-interference. We sought to optimize various modular components (ribosomal binding sites and fluorescent proteins) to ensure the rapid generation of fluorescent signals. Finally, the biosensors were implemented within a microchannel device to reduce sample consumption in point-of-care assays.

Stomach 3D Reconstruction Based on Virtual Chromoendoscopic Image Generation.

Gastric endoscopy is a standard clinical process that enables medical practitioners to diagnose various lesions inside a patient's stomach. If any lesion is found, it is very important to perceive the location of the lesion relative to the global view of the stomach. Our previous research showed that this could be addressed by reconstructing the whole stomach shape from chromoendoscopic images using a structure-from-motion (SfM) pipeline, in which indigo carmine (IC) blue dye-sprayed images were used to increase feature matches for SfM by enhancing stomach surface's textures. However, spraying the IC dye to the whole stomach requires additional time, labor, and cost, which is not desirable for patients and practitioners. In this paper, we propose an alternative way to achieve whole stomach 3D reconstruction without the need of the IC dye by generating virtual IC-sprayed (VIC) images based on image-to-image style translation trained on unpaired real no-IC and IC-sprayed images. We have specifically investigated the effect of input and output color channel selection for generating the VIC images and found that translating no-IC green-channel images to IC-sprayed red-channel images gives the best SfM reconstruction result.

Effect of Color Output Modification Approach (COMA) on the gray balance: A mismatch of device calibration, destination and source profiles, and halftone screening

The purpose of this applied research in the digital print production was to determine the influence of applied Color Output Modification Approaches (COMA) or Color Output Sequences (COS) to determine the colorimetric variations (COLVA) on the gray balance (GB) hue in a Color Managed Digital Printing Workflow (CMDPW). The experiment analyzed the application of eight COMA or COS on the digital color output. The data contained in this report are the result of an experiment conducted to test an accepted color management practice to gain a greater understanding of the presumptions associated with the application of correct print parameters (Calibration, Screening, Resolution, Source and Destination Profiles) of CMDPW. These parameters rely on the 4-C’s (Calibration, Characterization, Conversion and Control) of Color Managed Workflow (CMW). The experiment examined the eight COMA as independent groups (K = 8) using a one-way Analysis of Variance (ANOVA) with equal n’s method (at α = 0.05) to determine the significant colorimetric variations that exists among the [K = 8, N = 800, ni = 80, nt = 640] groups gray balance average hue deviations. With eight groups, a one-tailed, non-directional hypothesis was established. The conclusions of this study are based upon an analysis of the COLVA by ANOVA test data and associated findings. The data from the ANOVA revealed significant differences in the COLVA of the reproduction among the multiple COMA groups. The colorimetric data derived by the experiment suggest that selection of correct print parameters is an important step in a CMDPW as it relates to achieving accurate GB for a desired use/purpose.

Color Variation of the Up-Conversion Luminescence in Er3+-Yb3+ Co-Doped Lead Germanate Glasses and Microsphere Integrated Devices

Lead germanate glass samples co-doped with different Er3+/Yb3+ concentrations were prepared and the color variation of the up-conversion emissions in these glasses was observed using a 980 nm laser pump. A practical optical integrated device based on Er3+-Yb3+ co-doped lead germanate glass microsphere and a special fiber structure, consisting of single mode fiber (SMF), multimode fiber (MMF) and a suspended tri-core hollow fiber (STCHF) is described. As the pump light is coupled into the microsphere from the cores suspended inside the STCHF, the microsphere fixed in the air hole of the STCHF is excited and the up-conversion emissions are observed. Furthermore, when the pump power is increased, the luminescence output color of the microsphere can be readily tuned from yellow to green due to the change of the luminescence intensity ratio of the red to green emissions. This in-fiber microsphere resonator integrated device has the potential to be widely applied in multicolor displays, optical sensors and laser devices owing to its compact structure and excellent performance.

Up-conversion luminescence tuning induced by cross-relaxation processes in Gd2O3: Yb3+/Ho3+/Ce3+ nanoparticles

In this work, we reported the influences of Ce3+ doping on continuous and pulse 980 nm laser excited up-conversion luminescence of Gd2O3: Yb3+/Ho3+. Under continuous excitation at 980 nm, a 7.6-fold up-conversion red-to-green ratio enhancement was achieved by co-doping Ce3+ into Gd2O3: Yb3+/Ho3+, which could be attributed to two effective Ho3+-Ce3+ cross-relaxation processes. Besides, introducing Ce3+ also induced the more significant enhancement in the red to green intensity ratio with increasing the excitation pulse-widths of 980 nm laser in comparison to the sample without Ce3+. The results were contributed to better understand the influence of Ce3+ doping on the up-conversion luminescence of Ho3+, especially under the non-continuous excitation, endowing us with the more opportunities to control the up-conversion color output for satisfying diverse applications in a multitude of fields.