Multiple Emission Research Articles

Advancements in the Improvement of Optical Outcoupling Efficiency for Perovskite LEDs

In the past 10 years, the development of perovskite light-emitting diodes (PeLEDs) was fast. Due to the excellent properties of high brightness and color purity, multiple color emission, and cost-effective fabrication technology, PeLEDs have been very promising in semiconductor lighting and display applications. In an effort to achieve high-efficient PeLED devices, researchers have devoted themselves to explore and optimize the emitted materials and device structures. Among various research approaches, raising the optical outcoupling efficiency ( η out ) of PeLED through light management strategies is very important for further promoting device performances, which is due to that approximately 80% of the photons generated internally are captured or worn out in different optical modes in the device. In this review, the latest researches on optical outcoupling regulations in PeLED are outlined, which mainly focus on photophysical properties and implementation methods. As the key part of this review, implementation strategies are classified into the optimization of characteristics of functional materials (refractive index, film thickness, anisotropy, and photon recovery) and adjustment of device architecture (patterned nanostructures, photonic crystals, metal nanostructures, and external couplers). Additionally, a prospect of the future directions and development trend for this research field is presented in order to achieve ultra-efficient PeLED and future commercial applications.

Time-dependent room temperature phosphorescent colors from a sulfur-doped carbon dot-based composite for advanced information encryption and anti-counterfeiting applications

Sulfur doping regulates the bandgap of the carbon dots, and time-dependent afterglow color emission is realized in a carbon dot-based composite via the multiple triplet emissions with distinct lifetimes.

Low 18F-fluorodeoxyglucose dose positron emission tomography assisted by a deep-learning image-denoising technique in patients with lymphoma.

Patients with lymphoma receive multiple positron emission tomography/computed tomography (PET/CT) exams for monitoring of the therapeutic response. With PET imaging, a reduced level of injected fluorine-18 fluorodeoxyglucose ([18F]FDG) activity can be administered while maintaining the image quality. In this study, we investigated the efficacy of applying a deep learning (DL) denoising-technique on image quality and the quantification of metabolic parameters and Deauville score (DS) of a low [18F]FDG dose PET in patients with lymphoma. This study retrospectively enrolled 62 patients who underwent [18F]FDG PET scans. The low-dose (LD) data were simulated by taking a 50% duration of routine-dose (RD) PET list-mode data in the reconstruction, and a U-Net-based denoising neural network was applied to improve the images of LD PET. The visual image quality score (1 = undiagnostic, 5 = excellent) and DS were assessed in all patients by nuclear radiologists. The maximum, mean, and standard deviation (SD) of the standardized uptake value (SUV) in the liver and mediastinum were measured. In addition, lesions in some patients were segmented using a fixed threshold of 2.5, and their SUV, metabolic tumor volume (MTV), and tumor lesion glycolysis (TLG) were measured. The correlation coefficient and limits of agreement between the RD and LD group were analyzed. The visual image quality of the LD group was improved compared with the RD group. The DS was similar between the RD and LD group, and the negative (DS 1-3) and positive (DS 4-5) results remained unchanged. The correlation coefficients of SUV in the liver, mediastinum, and lesions were all >0.85. The mean differences of SUVmax and SUVmean between the RD and LD groups, respectively, were 0.22 [95% confidence interval (CI): -0.19 to 0.64] and 0.02 (95% CI: -0.17 to 0.20) in the liver, 0.13 (95% CI: -0.17 to 0.42) and 0.02 (95% CI: -0.12 to 0.16) in the mediastinum, and -0.75 (95% CI: -3.42 to 1.91), and -0.13 (95% CI: -0.57 to 0.31) in lesions. The mean differences in MTV and TLG were 0.85 (95% CI: -2.27 to 3.98) and 4.06 (95% CI: -20.53 to 28.64) between the RD and LD groups. The DL denoising technique enables accurate tumor assessment and quantification with LD [18F]FDG PET imaging in patients with lymphoma.

Reversible tri-state structural transitions of hybrid copper(i) bromides toward tunable multiple emissions

Synthetic control and tri-state structural transitions (112 ↔ 224 ↔ 246) of three hybrid copper bromides with different coordination geometries, which exhibit tunable optical property, are fristly discovered and investigated in hybrid copper halides.

Solvent-regulated multicolor-emissive carbon dots and their application in multicolor light-emitting diodes

Multicolor emissive carbon dots are achieved using a solvent regulation strategy, exhibiting multiple emission mechanisms.

A photoinduced electron-transfer strategy for switchable fluorescence and phosphorescence in lanthanide-based coordination polymers.

Smart optical materials with tunable fluorescence and room temperature phosphorescence (RTP) exhibit promising application prospects in the field of intelligent switches, information security, etc. Herein, a tetraimidazole derivative was grafted to one-dimensional lanthanum-diphosphonate through H-bonds, generating a coordination polymer (CP), (H4-TIBP)·[La2Li(H2-HEDP)4(H-HEDP)]·3H2O (termed La; TIBP = 3,3,5,5-tetra(imidazole-1-yl)-1,1-biphenyl; H4-HEDP = 1-hydroxyethylidene-1,1-diphosphonic acid) with a three-dimensional supramolecular structure. La shows dynamic fluorescence from blue to red and switchable monotonous yellowish-green RTP, which can be manipulated by reversible photochromism. It is worth noting that Eu3+/Tb3+-doped CPs exhibit time-resolved (red to yellow) and monotonous green afterglow, respectively, which can be attributed to multiple emissions with different decay rates. The dynamic and multicolor luminescence endows these CPs with potential for application in the domains of optical communications, multi-step encryption, and anti-counterfeiting. This work not only integrates color-adjustable fluorescence, switchable RTP, and photochromism in one material, but also realizes the manipulation of the resultant optical performances via photochromism, paving the pathway for the design and synthesis of smart optical materials.

Effect of Yb3+ concentration on the spectroscopic properties of Er3+/Yb3+ co-doped SiO2-TiO2 nanofiber

Er3+ has been gaining much interest due to the multiple emissions in both infrared and visible regions. Based on the previous study, SiO2-TiO2 have been proven to be an excellent host for Er3+. However, Er3+ exhibits a low absorption cross-section when doped into the silica-based host. Therefore, Yb3+ has been introduced into the matrix and acts as a sensitiser to increase the luminescence intensity. Er3+/Yb3+ co-doped 75SiO2-25TiO2 nanofiber with different Er3+/Yb3+ ratios were fabricated via the sol-gel electrospinning method. The FESEM result shows the diameter of the nanofibers in the range of 62 to 515 nm. The absence of any peak within the 3000-4000 cm-1 range in the FTIR spectra indicates the complete removal of the OH group. The XRD results imply that all samples were amorphous. The PL spectra showed strong green emission peaks, which were ascribed to 2H11/2 → 4I15/2 as well as red emission peaks attributed to 4F9/2 → 4I15/2 Er3+ transitions. The PL intensity was varied according to the Yb3+ concentration. The addition of Yb3+ was proven to aid the increment of PL intensity. Nevertheless, the PL intensity reduced when too high of Yb3+ concentration was used due to the concentration quenching effect.

Synthesis and analysis of Ag/olanzapine/cyclodextrin and Ag/Co/Olanzapine/cyclodextrin inclusion complex nanorods

ABSTRACT Silver-cobalt nanoparticles were synthesised using a chemical reduction technique. Olanzapine-cyclodextrin inclusion complex containing Ag and Ag/Co nanoparticles was examined using UV-Visible, fluorescence, computational method, FT-IR, differential scanning colorimeter, X-RD, FE-SEM, and TEM methods. A blue-shifted absorption maximum was seen in the presence of the OP/CD inclusion complex with silver and silver/cobalt nanoparticles. Multiple emission was noted in the α-CD and β-CD. TEM images conformed the formation of nanorods in Ag/OP/CD and Ag/Co/OP/CD. The pure isolated OP drug or Ag/OP/CD and Ag/Co/OP/CD do not exhibit any antibacterial activity.

(Invited) Luminescence Nanothermometers: Using Light to Detect Temperature

Rare earth doped nanoparticles have recently emerged as versatile luminescent probes for a number of biological applications resulting from their interesting photophysical properties. These nanoparticles can be excited with near-infrared (NIR) light, which is a strict requirement for biomedical applications due its light penetration capabilities. Furthermore, rare earth doped nanoparticles possess a multitude of 4f electronic energy states and excitation with NIR light can therefore lead to different excitation mechanisms. For example, following NIR excitation, the nanoparticles can undergo upconversion where multiple emissions are observed with energies higher than the excitation wavelength. Also, they can undergo conventional luminescence where emission at lower energies than the excitation wavelength can be observed (known as downshifted luminescence). Here, we show that it is possible to harness these various emissions (upconverted and downshifted) to design luminescence nanothermometers capable of detecting temperature in living organisms.

The Framework for Assessing Changes To Sea-level (FACTS) v1.0: a platform for characterizing parametric and structural uncertainty in future global, relative, and extreme sea-level change

Abstract. Future sea-level rise projections are characterized by both quantifiable uncertainty and unquantifiable structural uncertainty. Thorough scientific assessment of sea-level rise projections requires analysis of both dimensions of uncertainty. Probabilistic sea-level rise projections evaluate the quantifiable dimension of uncertainty; comparison of alternative probabilistic methods provides an indication of structural uncertainty. Here we describe the Framework for Assessing Changes To Sea-level (FACTS), a modular platform for characterizing different probability distributions for the drivers of sea-level change and their consequences for global mean, regional, and extreme sea-level change. We demonstrate its application by generating seven alternative probability distributions under multiple emissions scenarios for both future global mean sea-level change and future relative and extreme sea-level change at New York City. These distributions, closely aligned with those presented in the Intergovernmental Panel on Climate Change Sixth Assessment Report, emphasize the role of the Antarctic and Greenland ice sheets as drivers of structural uncertainty in sea-level change projections.

Attributions of emission-reduction and meteorological conditions to typical heavy pollution episodes in a cold metropolis, northeast China

Heavy pollution episodes frequently occurred in winter in northeast China due to the multiple anthropogenic emissions coupled with adverse meteorological conditions, which increased the difficulty of environmental pollution control. To better enact strategies for mitigating air pollution in the post-pandemic era, daily pollutant concentration monitoring and meteorological data were used to evaluate the changes and meteorological factors of air pollutants before (2019) and during (2020) the lockdown in Harbin City, northeast China. Moreover, typical pollution episodes under COVID-19 lockdown were identified, and their emission sources, meteorology conditions, and regional pollution transportation were analyzed. The results showed significant decreases in NO2, PM10 and CO, while O3 increased, and no differences in PM2.5 and SO2 during the lockdown compared with non-lockdown periods. It indicated that reduced activities of transportation resulted in reductions of NO2 concentrations by 16%, and stationary emission sources were less affected. Correlation between PM2.5 and O3 tended to change from positive to negative as the threshold of PM2.5 = 90 μg m−3, with the main controlling factor changed from their common gaseous precursors to meteorological conditions (temperature <0°C and wind speed <2 m s−1). Pollution days were concentrated in the COVID-19 lockdown period with PM2.5 as the primary pollutant. SO2 dominant pollution and PM2.5 dominant pollution were distinguished from six sustained heavy pollution events. PM2.5 and SO2 played essential roles in SO2 dominant pollution, which derived from local emissions of coal combustion and firework discharge. PM2.5 dominant pollution might be chemical transformed from coal burning, vehicle exhaust, and other secondary precursors, which was affected and aggravated by CO, NO2, high relative humidity and low wind speed affected by local emission and long-distance transport.

Evaluating the effects of climate change and chemical, physical, and biological stressors on nearshore coral reefs: A case study in the Great Barrier Reef, Australia.

An understanding of the combined effects of climate change (CC) and other anthropogenic stressors, such as chemical exposures, is essential for improving ecological risk assessments of vulnerable ecosystems. In the Great Barrier Reef, coral reefs are under increasingly severe duress from increasing ocean temperatures, acidification, and cyclone intensities associated with CC. In addition to these stressors, inshore reef systems, such as the Mackay-Whitsunday coastal zone, are being impacted by other anthropogenic stressors, including chemical, nutrient, and sediment exposures related to more intense rainfall events that increase the catchment runoff of contaminated waters. To illustrate an approach for incorporating CC into ecological risk assessment frameworks, we developed an adverse outcome pathway network to conceptually delineate the effects of climate variables and photosystem II herbicide (diuron) exposures on scleractinian corals. This informed the development of a Bayesian network (BN) to quantitatively compare the effects of historical (1975-2005) and future projected climate on inshore hard coral bleaching, mortality, and cover. This BN demonstrated how risk may be predicted for multiple physical and biological stressors, including temperature, ocean acidification, cyclones, sediments, macroalgae competition, and crown of thorns starfish predation, as well as chemical stressors such as nitrogen and herbicides. Climate scenarios included an ensemble of 16 downscaled models encompassing current and future conditions based on multiple emission scenarios for two 30-year periods. It was found that both climate-related and catchment-related stressors pose a risk to these inshore reef systems, with projected increases in coral bleaching and coral mortality under all future climate scenarios. This modeling exercise can support the identification of risk drivers for the prioritization of management interventions to build future resilient reefs. Integr Environ Assess Manag 2024;20:401-418. © 2023 Norwegian Institute for Water Research and The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Fabrication of high-performance RT-NH3 gas sensor based on Cu and La co-doped ZnO films through a facile drop-casting method

In this work, undoped ZnO, 2 % Cu-doped ZnO, 2 % La-doped ZnO and 2 % (Cu:La) co-doped ZnO thin films are deposited on glass substrates using the facile drop-casting method, and their physical characteristics were investigated for the gas sensing application. The X-ray diffraction (XRD) patterns confirmed the hexagonal wurtzite structure and increase in crystallinity for the doped samples. Field Emission Scanning Electron Microscopy (FESEM) images revealed a significant change in morphology from the granular particles to densely packed nanoplates-like morphology for (Cu:La) co-doped ZnO. The doped samples exhibited a red shift in absorption edge and shrinkage of the optical bandgap. Multiple emission peaks in photoluminescence (PL) spectra indicated the presence of defect level in the material. It was discovered that Cu-doped and La-doped ZnO thin films had a considerable NH3 sensing response at ambient temperature. The gas response was remarkably enhanced to 341 % for (Cu:La) co-doped ZnO film and a quicker response/recovery time of 80/10 s for 250 ppm NH3. The (Cu:La) co-doped ZnO can serve as a feasible alternative for pure ZnO gas sensors.

Smart-Responsive HOF Heterostructures with Multiple Spatial-Resolved Emission Modes toward Photonic Security Platform.

Luminescent hydrogen-bonded organic frameworks (HOFs) with the unique dynamics and versatile functional sites hold great potential application in information security, yet most of responsive HOFs focus on the single-component framework with restrained emission control, limiting further applications in advanced confidential information protection. Herein, the first smart-responsive HOF heterostructure with multiple spatial-resolved emission modes for covert photonic security platform is reported. The HOF heterostructures are prepared by integrating different HOFs into a single microwire based on a hydrogen-bond-assisted epitaxial growth method. The distinct responsive behaviors of HOFs permit the heterostructure to simultaneously display the thermochromism via the framework transformation and the acidichromism via the protonation effect, thus generating multiple emission modes. The dual stimuli-controlled spatial-resolved emission modes constitute the fingerprint of a heterostructure, and enable the establishment of the smart-responsive photonic barcode with multiple convert states, which further demonstrate the dynamic coding capability and enhanced security in anticounterfeiting label applications. These results offer a promising route to design function-oriented smart responsive HOF microdevices toward advanced anticounterfeiting applications.

Two-stage assessment: Towards a novel and holistic evaluation of urban geographically isolated wetland sustainability under global warming-induced dryness and loss

Global wetlands are vital for carbon sequestration and providing ecosystem services in sustainable cities. However, urban wetlands, particularly geographically isolated wetlands (GIWs), face threats from climate change and rapid urbanization. The vulnerability of GIWs, considering the critical water flux exchanges with their surroundings, remains unclear. This study proposes a groundbreaking two-stage assessment framework for evaluating GIW sustainability. The first stage quantifies dryness risk by assessing the absence of surface water storage. The second stage evaluates wetland loss risk by examining unsustainable conditions of lacking saturated soil. The framework utilizes a hydrological model incorporated with 20 Global Climate Models (GCMs) under multiple greenhouse gas emission scenarios. Moreover, Taguchi optimization is firstly introduced the hydro-climate field to improve simulation efficiency, with a new modification by a modified robust design. Results indicate an average 26 cm drop in the GIW water table by 2099 under moderate GCM scenarios, with an 86% risk of drying and a 64% risk of transitioning to loss. Notably, GIWs face over twice the risk of loss compared to upland areas, but demonstrate an advantage in water reservation under climate change. By proposing and employing this innovative approach, this research provides valuable insights into the interconnectedness of GIWs, offering a more comprehensive understanding of long-term urban ecological integrity. The findings also contribute to the long-term sustainability of urban wetlands and enhance the resilience of urban ecosystems.

Dosimetric properties of Tb-doped CaGdAlO4 single crystals

Tb-doped CaGdAlO4 crystals were investigated and showed photoluminescence peaks due to Tb3+. Likewise, multiple emission peaks derived from Tb3+ were detected in the optically stimulated luminescence. According to the thermally stimulated luminescence dose response, the detection limit was 1 µGy which was superior to several commercial dosimeters.

A comparative assessment of the development of GHG emission criteria and benchmark values for buildings in Norway

GHG emission criteria and benchmark values for buildings are being developed internationally to meet climate goals in the Paris agreement. However, there is a distinct lack of harmonisation in approaches making it difficult to compare construction projects or implement and apply benchmarking at a national or international level. Norway is no exception. In recent years, multiple GHG emission criteria and benchmark values have been developed and tested to measure and evaluate the environmental sustainability of Norwegian buildings during their life cycle. These include proposals from Ydalir Masterplan, the research centre for zero emission buildings in smart cities, FutureBuilt ZERO and BREEAM-NOR v6.0. This paper presents and reviews these approaches in relation to recent Norwegian building code requirements for the reporting of GHG emissions. The paper compares the approaches in terms of methodologies, typologies, reference study period, life cycle modules, building parts, limitations and advantages. The results show that there are large differences in approaches which leads to a disparity in benchmarking levels. Further work is required to harmonise and create an accepted branch standard for benchmarking GHG emissions from buildings for the construction industry in Norway. In addition, it would be of benefit to establish a national database for GHG emission accounting so that better benchmark values can be established.

Dynamically Downscaled Projections of Phenological Changes across the Contiguous United States

Abstract Phenological indicators (PI) are used to study changes to animal and plant behavior in response to seasonal cycles, and they can be useful to quantify the potential impacts of climate change on ecosystems. Here, multiple global climate models and emission scenarios are used to drive dynamically downscaled simulations using the WRF Model over the contiguous United States (CONUS). The wintertime dormancy of plants [chilling units (CU)], timing of spring onset [extended spring indices (SI)], and frequency of proceeding false springs are calculated from regional climate simulations covering historical (1995–2005) and future periods (2025–2100). Southern parts of the CONUS show projected CU decreases (inhibiting some plants from flowering or fruiting), while the northern CONUS experiences an increase (possibly causing plants to break dormancy too early, becoming vulnerable to disease or freezing). Spring advancement (earlier SI dates) is projected, with decadal trends ranging from approximately 1–4 days per decade over the CONUS, comparable to or exceeding those found in observational studies. Projected changes in risk of false spring (hard freezes following spring onset) vary across members of the ensemble and regions of the CONUS, but generally western parts of the CONUS are projected to experience increased risk of false springs. These projected changes to PI connote significant effects on cycles of plants, animals, and ecosystems, highlighting the importance of examining temperature changes during transitional seasons. Significance Statement This study examines how phenological indicators, which track the life cycles of plants and animals, could change from 2025 to 2100 as simulated in a regional climate model over the contiguous United States. Chilling units quantify the presence of cooler weather that can benefit plants prior to their growing season. They are projected to decrease in the southern United States, possibly inhibiting agricultural production. Spring onset is projected to occur earlier in the year, advancing by 1–4 days on average over each future decade. Risk of false springs (damaging hard freezes after spring onset) increases in the western United States. Our findings highlight the need to understand effects of climate change during transitional seasons, which can impact agriculture and ecosystems.

A multi‐emission‐driven efficient network design for green hub‐and‐spoke airline networks

AbstractThe green hub‐and‐spoke airline network (GHSAN) is emerging as a dominant feature due to its excellent economic and environmental‐friendly capabilities. However, environmental GHSAN designs still have some concerns, including single pollutant‐domain oversimplification and lack of comprehensive network‐level operation impacts. This paper proposes a multi‐emission‐driven efficient network design approach for GHSAN, utilizing a system, green, and user threefold optimization methodology. The approach includes a multi‐objective optimization model and a two‐layer solving method. The multi‐objective optimization aims at minimizing multiple emissions, including carbon dioxide, carbonic oxide hydrocarbon, and nitric oxide, while also considering transportation system costs and journey user costs. A two‐layer optimization algorithm is adopted to address different scales of optimization. Real‐world results demonstrate that the proposed method mitigates environmental impact and user costs and increases overall airline density in airline networks. The proposed method can have a 16.29% reduction in green‐fold (10 nodes) and a 12.06% decrease in user costs for the user‐fold (10 nodes). As the number of nodes (15, 25, 50 nodes) and hubs (3, 4, 5, 6, 7 hubs) increase, the genetic algorithm (GA) proves to be more efficient and suitable in large‐scale GHSAN. This work is further significant for the long‐term and sustainable development of the future air transport industry.

Excitation-Selective and Double-Emissive Lead-Free Binary Hybrid Metal Halides for White Light-Emitting Diode and X-Ray Scintillation.

Zero-dimensional (0D) organic metal halides comprising heterogeneous metal cations in single phase can achieve multiple luminous emissions enabling them toward multifunctional light-emitting applications. Herein, A novel single crystal of (C8H20N)4SbMnCl9 containing two luminescent centers of [SbCl5]2- pentahedrons and [MnCl4]2- tetrahedrons is reported. The large distance between Sb-Sb, Mn-Mn, and Sb-Mn as well as theory calculation indicate negligible interaction between individual centers, thus endowing (C8H20N)4SbMnCl9 with excitation-dependable and efficient luminescence. Under near-UV excitation, only orange emission originates from self-trapped excitons recombination in [SbCl5]2- pentahedron occurs with photoluminescence quantum yield (PLQY) of 91.5%. Under blue-light excitation, only green emission originating from 4T1-6A1 transition of Mn2+ in [MnCl4]2- tetrahedrons occurs with PLQY of 66.8%. Interestingly, upon X-ray illumination, both emissions can be fully achieved due to the high-energy photon absorption. Consequently, (C8H20N)4SbMnCl9 is employed as phosphors to fabricate white light-emitting diodes optically pumped by n-UV chip and blue-chip thanks to its excitation-dependable property. Moreover, it also shows promising performance as X-ray scintillator with low detection limit of 60.79 nGyair S-1, steady-state light yield ≈54% of commerical scintillaotr LuAG:Ce, high resolution of 13.5 lpmm-1 for X-ray imaging. This work presents a new structural design to fabricate 0D hybrids with multicolor emissions.