State Emission Research Articles

Precisely Prepared Hierarchical Micelles of Polyfluorene-block-Polythiophene-block-Poly(phenyl isocyanide) via Crystallization-Driven Self-Assembly.

The precise preparation of hierarchical micelles is a fundamental challenge in modern materials science and chemistry. Herein, poly(di-n-hexylfluorene)-block-poly(3-tetraethylene glycol thiophene) (poly(1m-b-2n)) diblock copolymers and polyfluorene-block-polythiophene-block-poly(phenyl isocyanide) triblock copolymers were synthesized using a one-pot process via the sequential addition of corresponding monomers using a Ni(II) complex as a single catalyst for living/controlled polymerization. The crystallization-driven self-assembly of amphiphilic conjugated poly(1m-b-2n) led to the formation of nanofibers with controlled lengths and narrow dispersity. The block copolymers exhibited white, yellow, and red emissions in different self-assembly states. By using uniform poly(1m-b-2n) nanofibers as seeds, introducing the polyfluorene-block-polythiophene-block-poly(phenyl isocyanide) triblock polymer as a unimer in the seed growth process, and adjusting the structure of the poly(phenyl isocyanide) block and the polarity of self-assembly solvent, A-B-A triblock micelles, multiarm branched micelles, and raft micelles were prepared.

Experimental and Computational Investigation of the Photophysical Properties of a Series of Luminescent D−A−D’ and D−A−A’ Pyrimidines

AbstractPyrimidines, a prominent isomer class of diazines, are promising molecular constituents of electron‐deficient luminescent and hole‐transport materials. Here, we report the fluorescence lifetimes and describe the electronic structures and character of low‐lying emissive excited states of a series of synthetically accessible donor‐acceptor‐donor (D−A−D′) and donor‐acceptor‐acceptor (D−A−A′) type pyrimidines, including both all‐organic and hybrid organic‐organometallic analogues. We find that strategically varying the aryl substituents on a pyrimidine enables tuning of the character of the luminescent excited states from charge‐transfer (CT) to locally excited (LE) states, which then differ in their sensitivity to their environment. This study suggests structural handles for controlling the photophysics of arylpyrimidines relevant to a variety of applications for luminescent materials.

Heralded Generation of Correlated Photon Pairs from CdS/CdSe/CdS Quantum Shells.

Quantum information processing demands efficient quantum light sources (QLS) capable of producing high-fidelity single photons or entangled photon pairs. Single epitaxial quantum dots (QDs) have long been proven to be efficient sources of deterministic single photons; however, their production via molecular-beam epitaxy presents scalability challenges. Conversely, colloidal semiconductor QDs offer scalable solution processing and tunable photoluminescence, but suffer from broader linewidths and unstable emissions. This leads to spectrally inseparable emission from exciton (X) and biexciton (XX) states, complicating the production of single photons and triggered photon pairs. Here, we demonstrate that colloidal semiconductor quantum shells (QSs) achieve significant spectral separation (∼75-80 meV) and long temporal stability of X and XX emissive states, enabling the observation of exciton-biexciton bunching in colloidal QDs. Our low-temperature single-particle measurements show cascaded XX-X emission of single photon pairs for over 200 s, with minimal overlap between X and XX features. The X-XX distinguishability allows for an in-depth theoretical characterization of cross-correlation strength, placing it in perspective with photon pairs of epitaxial counterparts. These findings highlight a strong potential of semiconductor quantum shells for applications in quantum information processing.

The state of greenhouse gas emissions in some fields of the agricultural sector in Hanoi

The state of greenhouse gas emissions in some fields of the agricultural sector in Hanoi

Synthesis, Photophysical Properties, and Optical Limiting Behavior of Organometallic Complexes: Influence of Metal Centers and Conjugated Diimine Ligands

Four organometallic complexes featuring identical conjugated diimine ligands and varying transition metal centers (Rh(III), Ir(III), Ru(II), and Os(II)) were synthesized. A comprehensive investigation of the photophysical properties of these complexes and their corresponding diimine ligands was conducted by UV‐vis absorption, emission, and transient absorption (TA) spectroscopy, as well as optical power limiting (OPL) measurements. The incorporation of fluorene components with alkyl chains enhanced the π‐conjugation of the ligand, prevented intermolecular π‐π stacking, and improved complex solubility. The diimine ligands showed a slight solvation effect in their emission spectra, indicating that the main property of their emissive state was intramolecular charge transfer (CT). According to the valence states of the four complexes, they can be divided into two classes (Rh(III), Ir(III)) and (Ru(II), Os(II)). For TA spectrum, the former group exhibited positive ΔOD values across the 400‐800 nm range, while the latter showed large inverted peaks at 420‐500 nm due to significant ground‐state absorption in this wavelength range. Additionally, the optical limiting conduct of the complexes observed the order: 1d > 1a > 1c > 1b. Complex 1d exhibits powerful reverse saturable absorption (RSA) properties at 532 nm and could probably be used as an wonderful nonlinear absorbing material.

Modulating Charge-Transfer Excited States of Multiple Resonance Emitters via Intramolecular Covalent Bond Locking.

Advanced multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters with high efficiency and color purity have emerged as a research focus in the development of ultra-high-definition displays. Herein, we disclose an approach to modulate the charge-transfer excited states of MR emitters via intramolecular covalent bond locking. This strategy can promote the evolution of strong intramolecular charge-transfer (ICT) states into weak ICT states, ultimately narrowing the full-width at half-maximum (FWHM) of emitters. To modulate the ICT intensity, two octagonal rings are introduced to yield molecule m-DCzDAz-BNCz. Compounds m-CzDAz-BNCz and m-DCzDAz-BNCz exhibit bright light-green and green fluorescence in toluene, with emission maxima of 504 and 513 nm, and FWHMs of 28 and 34 nm, respectively. Sensitized organic light-emitting diodes (OLEDs) employing emitters m-CzDAz-BNCz and m-DCzDAz-BNCz exhibit green emission with peaks of 508 and 520 nm, Commission Internationale de L'Eclairage (CIE) coordinates of (0.12, 0.65) and (0.19, 0.69), and maximum external quantum efficiencies (EQEs) of 30.2 % and 32.6 %, respectively.

Controlled Photooxidation via Singlet Oxygen Generation by Triplet Harvesting in a Heavy Atom Free Pure Organic Dithienylethene-Naphthalene Diimide.

Noninvasive control over the reversible generation of singlet oxygen (1O2) has found the enormous practical implications in the field of biomedical science. However, metal-free pure organic emitters, connected with a photoswitch, capable of generating "on-demand" 1O2 via triplet harvesting remain exceedingly rare; therefore, the utilization of these organic materials for the reversible control of singlet oxygen production remains at its infancy. Herein, an ambient triplet mediated emission in quinoline-dithienylethene (DTE)-core-substituted naphthalene diimide (cNDI) derivative is unveiled via delayed fluorescence. The quinoline-DTE-cNDI triad displayed enhanced photoswitching efficiency via double FRET mechanism. It was found to have direct utilization in controlled photosensitized organic transformations via efficient generation of singlet oxygen (yield ΦΔ~0.55 in DCM and 0.73 in methanol). The designed molecule exhibits a long-lived emission (τ∼1.1 μs) and very small singlet-triplet splitting (ΔEST) of 0.13 eV empowering it to display delayed fluorescence. Comprehensive steady state and time-resolved emission spectroscopy (TRES) analyses along with DFT calculations offer detailed understandings into the excited-state manifolds of organic compound and energy transfer (ET) pathways involved in 1O2 generation.

Structural Aspects, Binding Interactions, Biological Activity of Co(II)‐ and Ni(II)‐N′‐(2‐fluorobenzoyl)benzo[d]thiazole‐2‐carbohydrazide Chelatess

ABSTRACTN′‐(2‐Fluorobenzoyl)benzo[d]thiazole‐2‐carbohydrazide (OFBBTCH, HL) and its chelates with Co(II) and Ni(II) have been synthesized and characterized by elemental analysis, liquid chromatography‐mass spectrometry (LC–MS), Fourier transform infrared spectroscopy (FT‐IR), ultra‐violet visible (UV–vis), nuclear magnetic resonance (NMR) spectroscopy, thermogravimetric analysis (TGA), and powder X‐ray diffraction. The conductance measurements reveal that the chelates are non‐electrolytic, and the spectral analysis indicates octahedral geometry of the chelates. The kinetic and thermodynamic parameters were obtained by Coats–Redfern relations, which shows positive Gibbs's free energy and negative entropy for both chelates. The equilibrium studies carried out by pH‐metry revealed the dissociation constant (pKa) of OFBBTCH as 8.13 and the formation of 1:1 and 1:2 Co(II)‐L and Ni(II)‐L complexes in solution. The CT‐DNA binding studies carried out by electron absorption, fluorescence quenching, steady state emissions and viscosity studies revealed hyperchromism and groove binding for HL and chelates. The Kb values calculated from electron absorption studies are 2.4 × 106, 4 × 106, and 9 × 106 M−1, from the fluorescence quenching studies Ksv values are 0.1722, 0.278, and 0.748 M−1, and Kapp values are 5.9 × 104, 1.3 × 105, and 2.9 × 105 M−1 for HL, Co(II)‐OFBBTCH and Ni(II)‐OFBBTCH, respectively. Bovine serum albumin (BSA) and human serum albumin (HSA) binding interactions were carried out by electron absorption and fluorescence quenching studies. The light switching properties of the chelates, the hydrolytic and oxidative cleavage of CT‐DNA, and the antioxidant properties were evaluated. Anti‐microbial studies carried out by pour plate method showed high activity for Ni(II)‐OFBBTCH chelate. Cytotoxicity of the compounds was performed for HeLa and MCF cell lines by MTT assay. Molecular docking studies revealed the docking of HL and Co(II)‐HL at the minor groove, and Ni(II)‐HL was docked at the major groove with hydrogen bonding.

Chiral Organometallic Complexes Derived from Helicenic N-Heterocyclic Carbenes (NHCs): Design, Structural Diversity, and Chiroptical and Photophysical Properties.

ConspectusRecently, helicene derivatives have emerged as an important class of molecules with potential applications spanning over asymmetric catalysis, biological activity, magnetism, spin filtering, solar cells, and polymer science. To harness their full potential, especially as emissive components in circularly polarized organic light-emitting diodes (CP-OLEDs), generating structural chemical diversity and understanding the resulting photophysical and chiroptical properties are crucial. In this Account, we shed light on chemical engineering combining helicene and N-heterocyclic carbene (NHC) chemistries to create transition-metal complexes with unique architectures and describe their photophysical and chiroptical attributes. The σ-donating and π-accepting capabilities of the helically chiral π-conjugated NHCs endow the complexes with remarkable structural and electronic features. These characteristics manifest in phenomena such as chirality induction, very long-lived phosphorescence, and strong chiroptical signatures (electronic circular dichroism and circularly polarized luminescence).We describe the different classes of ligands primarily developed in our group by classifying them according to their connection between the helicenic moiety and the imidazole precursor. This connection is essential in determining the degree of π-conjugation and characterizing the emissive state. We comprehensively discuss 6-coordinate, 4-coordinate, and 2-coordinate complexes, delving into their structural nuances and examining how the interplay between metals and auxiliary ligands shapes their photophysical properties, with interpretations enriched by DFT calculations. Helicenes are known to promote intersystem crossing thanks to strong spin-orbit coupling, while metals offer robust frameworks leading to a variety of molecular architectures with specific topologies together with distinct excited-state properties. The electronic configurations and energy levels of the ligand and metal orbitals thus significantly modulate the photophysical and chiroptical behaviors of these complexes. In-depth analysis of chiroptical properties, notably electronic circular dichroism and circularly polarized luminescence, emphasizes the influence of different stereogenic elements on the chiroptical responses across various energy ranges with appealing "match-mismatch" effects. Finally, we describe future prospects of helicene NHCs, particularly in the context of emerging research on cost-effective and abundant transition metals for materials science and for photocatalysis. Indeed, the inherent long-lived MLCT, excited-state delocalization, structural rigidity, and intrinsic chirality of these complexes present intriguing avenues for future investigations.

Observation of Three-Photon Cascaded Emission from Triexcitons in Giant CsPbBr3 Quantum Dots at Room Temperature.

Colloidal semiconductor nanocrystals have long been considered a promising source of time-correlated and entangled photons via the cascaded emission of multiexcitonic states. The spectroscopy of such cascaded emission, however, is hindered by efficient nonradiative Auger-Meitner decay, rendering multiexcitonic states nonemissive. Here we present room-temperature heralded spectroscopy of three-photon cascades from triexcitons in giant CsPbBr3 nanocrystals. We show that this system exhibits second- and third-order correlation function values, g(2)(0) and g(3)(0,0), close to unity, identifying very weak binding of both biexcitons and triexcitons. Combining fluorescence lifetime analysis, photon statistics, and spectroscopy, we can readily identify emission from higher multiexcitonic states. We use this to verify emission from a single emitter despite high emission quantum yields of multiply excited states and comparable emission lifetimes of singly and multiply excited states. Finally, we present potential pathways toward control of the photon number statistics of multiexcitonic emission cascades.

Three-State Hidden Markov Model for Spectrum Prediction in Cognitive Radio Networks

The exponential growth and proliferation of wireless devices for different wireless applications have led to the emergence of cognitive radio network (CRN) for optimal utilization of scarce spectrum resources. However, these resources have grossly been under-utilized due to the inaccurate spectrum predictions. Existing spectrum occupancy and prediction techniques which rely on 2-state hidden Markov model (HMM) results in false alarm or missed detection caused by noisy or incomplete observable effects. In this paper, a 3-state HMM spectrum occupancy and prediction technique in CRNs is proposed. The transmission, emission and initial state probabilities of the proposed 3-state HMM parameters were derived based on the three canonical problems associated with HMM. The evaluation, decoding and learning problems were solved using Forward algorithm, Viterbi algorithm and the Baum-Welch algorithm, respectively. The performance of the proposed 3-state HMM spectrum prediction technique was evaluated using prediction accuracy, probability of detection and spectrum utilization efficiency. The simulation results obtained revealed that the 3-state HMM outperformed the 2-state HMM spectrum prediction technique by 24.1% in prediction accuracy.

Exploring Transient States of PAmKate to Enable Improved Cryogenic Single-Molecule Imaging.

Super-resolved cryogenic correlative light and electron microscopy is a powerful approach which combines the single-molecule specificity and sensitivity of fluorescence imaging with the nanoscale resolution of cryogenic electron tomography. Key to this method is active control over the emissive state of fluorescent labels to ensure sufficient sparsity to localize individual emitters. Recent work has identified fluorescent proteins (FPs) that photoactivate or photoswitch efficiently at cryogenic temperatures, but long on-times due to reduced quantum yield of photobleaching remain a challenge for imaging structures with a high density of localizations. In this work, we explore the photophysical properties of the red photoactivatable FP PAmKate and identify a 2-color process leading to enhanced turn-off of active emitters, improving localization rate. Specifically, after excitation of ground state molecules, we find that a transient state forms with a lifetime of ∼2 ms under cryogenic conditions, which can be bleached by exposure to a second wavelength. We measure the response of the transient state to different wavelengths, demonstrate how this mechanism can be used to improve imaging, and provide a blueprint for the study of other FPs at cryogenic temperatures.

Can technology in terms of finance, environment, and communication boost food production while facilitating a low-carbon transition? Evidence from a high-tech and low-tech state

The need to revamp the food system to combat climate change is growing. This initiative faces a major challenge: redesigning the agricultural system to increase food production (FOP) and attain sustainable development objectives simultaneously. Information and communication technologies (ICT), financial innovations, and environmental technology define a global community of shared futures, making it essential to consider whether these technologies can equally “enhance food production and reduce greenhouse gas (GHG) emissions” in agriculture in high-tech and low-tech states. The study examined the direct and indirect effects of these technologies on food production in China and Nigeria using the ARDL model. We controlled for climate factors such as precipitation, agricultural emissions, and temperature, plus agricultural factors like fertilizer consumption and land use. The findings indicate the following: 1) Financial innovation has a dual effect of increasing food production and decreasing agricultural emissions in both states. 2) Environmental technology lessens agricultural emissions in China but confirmed a dual role in Nigeria. 3) ICT directly increases (decreases) food production in China (Nigeria) as well as harms environmental quality in both states. The study found positive impact of land use, fertilizer consumption, and temperature on food production. Moreover, causality outcomes confirm the agricultural sector's environmental impact. To promote sustainable agriculture, the research suggested government and financial institutions lease agriculture machinery and offer internet based interest-free financing.

Exploring the interaction between derivatives of urea with resorcinol-based acridinedione dyes by employing fluorescence methods and molecular docking approach

Akyl urea derivatives, either symmetrical or unsymmetrical in nature possessing a free N-H or N-alkyl moieties in the molecular framework of urea governs the excited state properties of acridinedione dye (ADR1) which is a resorcinol-based derivative. Fluorescence enhancement (FE) of ADR1 dye is observed on the addition of unsymmetrical urea derivatives, whereas a decrease in the fluorescence intensity resulted upon the addition of symmetrical urea derivatives. The nature of the urea derivatives controls the suppression of photoinduced electron transfer (PET) via space, which is the cause of the FE. FQ results from the donor and acceptor moieties of ADR1 dye promoting the PET process. Urea (U), symmetrical and unsymmetrical urea derivatives (except Tetramethyl urea (TMU)) results no significant shift of the localized excited (LE) state emission of ADR1 dye. Studies of the ADR1 dye’s fluorescence lifetime in the presence of urea compounds show a significant increase in lifetime. This phenomenon is explained by a significant difference in the hydrogen-bonding (HB) pattern, which causes variationin the microenvironment created by thesolute molecules in the aqueous phase. Both the hydrophobic effects of the alkyl group substituents in the urea molecular framework and the HB interactions between the solute and solvent influence the excited state features of ADR1 dye. Further, the role of urea derivatives and ADR1 dye (both are considered as competitive guest molecules) energetics and molecular interactions were studied in the presence of host molecule, Human Serum Albumin (HSA). The binding energy (BE) and several bimolecular interactions driven by urea derivatives in the presence of ADR1-HSA complex in comparison with that of urea derivatives-HSA complex were investigated by molecular docking (Mol.Doc) methodology. Incorporating theoretical research along withsteady state and time-resolved fluorescence investigations proved to be an effective method to evaluate the interactions of competing solutes comprising bothhydrophobic and HB functional groups.

Manipulation of defect state emission in Zn chalcogenide quantum dots and their effects on chlorophyll spectral response

Water soluble Zn based quantum dots (QDs) are of interest due to their biocompatibility and less toxic features. They have been frequently used in studies related to biotechnology, especially in agriculture studies. However, to control the optical properties of Zn based QDs has still been a challenge. In this work, the defect state emission of ZnSe QDs was successfully controlled through two different routes; 1) By creating a sulfur rich outer region around the Se rich core 2) By changing the capping agent. Gradient alloyed ZnSeS QDs with Se rich core and S rich outer region were successfully synthesized with two different capping agents; N-Acetyl-L-Cysteine (NAC) and 3-Mercaptopropionic Acid (3-MPA). The contribution of emission originated from surface-defects almost disappeared in NAC capped ZnSeS QDs, with causing a significant increase in photoluminescence quantum yield. The interaction between Zn based QDs with chlorophyll molecules was also investigated. The absorption capacity of chlorophylls significantly enhanced upon interaction with 3-MPA capped ZnSeS QDs. Also, the spectral response of chlorophylls could be modulated through interaction with 3-MPA capped ZnSeS QDs, which could be manipulated by using ZnSeS QDs with different chemical composition. Our results indicated that ZnSeS QDs have potential to be used in agriculture, which could act as a modulator of light-harvesting capacity of chlorophylls. The ability to modulate chlorophyll spectral responses through QD interaction opens new possibilities for optimizing light utilization in photosynthetic organisms, thereby contributing to enhanced crop yields and more efficient use of light energy in natural and artificial ecosystems.

Comparison of aerosol number size distribution and new particle formation in summer at alpine and urban regions in the Guanzhong Plain, Northwest China

Ultrafine particles play a crucial role in understanding climate change, mitigating adverse health effects, and developing strategies for air pollution control. However, the factors influencing the occurrence and development of new particle formation (NPF) events, as well as the underlying chemical mechanisms, remain inadequately explained. This study compared number concentrations and size distributions of atmospheric ultrafine particles at Xi'an (urban area) and the summit of Mt. Hua (alpine region) in summer to investigate the NPF mechanism and particle growth in both clean and polluted areas of the Guanzhong Plain. The average particle number concentration in Xi'an was significantly higher than that at Mt. Hua. The diurnal variation of total particle number concentration differed between Xi'an and Mt. Hua indicating a divergence in influencing factors. The size distributions in Xi'an varied across different timescales and weather conditions, whereas Mt. Hua exhibited little variation. This stability at Mt. Hua is attributed to its cleaner background atmosphere and the steady influx of aging particles with larger diameters transported from the free atmosphere. In both areas, geometric mean diameters (GMDs) were inversely proportional to particle number concentrations suggesting that increase in particle numbers were primarily due to the generation of smaller particles. The potential governing factors for NPF events differed somewhat between the urban and mountainous stations. In the urban area, intense local stationary and mobile emission sources promoted the growth of newly formed nanoparticles, with ozone-oxidized condensable vapors serving as key precursors. In contrast, at the mountainous station, NPF process were significantly influenced by anthropogenic precursors from long-range transport and locally emitted biogenic organics. The rapid increase in ultrafine particle concentrations primarily poses serious health risks and degrades air quality in urban areas, while also contributing to climate-related effects in alpine regions.

Suzuki-Miyaura coupling reaction: Blue-yellow emitting AIE active dyes for organic electronics

A series of eight novel donor‒acceptor (D─A) based 2,3-di(thiophen-2-yl)quinoxaline derivatives 2–9 were prepared by modulating donor species on quinoxaline core with Palladium catalyzed Suzuki–Miyaura ‘C–C bond’ coupling reaction. The synthesized molecules were fully characterized and studied for impact of D–A interaction on opto-electrochemical properties. Absorption spectra of 2–9 display intramolecular charge transfer (ICT) transitions in the range of 388–414 nm. Dyes shows positive solvatochromism and emit in blue‒yellow region with emission maxima 444−550 nm on excitation at their respective ICT maxima in toluene, chloroform, DCM, DMSO and neat solid film. Further, solid state emission was studied for aggregation‒induced emission (AIE) effect in THF–water system due to the nanoparticles formation, as confirmed by FEG‒SEM technique. The HOMO and LUMO energy level for compounds 2–9 were measured by cyclic voltammetry and found in the range of −5.15 to −5.94 eV and −2.81 to −3.39 eV. Theoretical studies of molecules were also carried out by using DFT and TD‒DFT calculations. The comparable HOMO and LUMO energy levels with reported ambipolar materials and efficient solid-state emission make synthesized compounds potential candidate for solid state emissive, ambipolar charge transporting materials in organic electronics.

Formation of a combined electron-hole emission state in the LiRbSO4 – Eu phosphor

In the irradiated phosphor 4 LiRbSO Eu , the mechanisms of formation of the induced or combined electron-emitting state at 3.1-2.94 eV were studied using optical and thermal activation spectroscopy methods. It has been shown experimentally that the combined electron-emitting state of the phosphor is formed from the electron states of impurity and intrinsic electron and hole trapping centers of 24Eu SO   and 34 4 SO SO . Electron and hole trapping centers are created by irradiating the phosphor with photons exceeding the width of the forbidden band of the matrix, where free electrons are created in the conduction band and a hole in the valence band. The trapping center is formed by the capture of free electrons by impurities and anionic complexes according to the reaction 3 2 Eu e Eu      ,2 34 4 SO e SO    . In one process with electron centers, holes in the form of 24SO are localized. Thus, impurity and intrinsic 2 4Eu SO   and 34 4 SO SO  electron-hole trapping centers are formed. Similarly, trapping centers are formed as a result of charge transfer from the excited anion of the 24SO complex to the 3Eu  impurities and to the neighboring 2 4 SO anions according to the reaction ( 2 3 O Eu   ) and ( 2 24O SO  ), and localized holes are also formed in one act along with it. Combined electron-emitting states consisting of impurity and intrinsic electron states are excited by photons with energies of ~4.0 eV and ~4.5 eV.

Programmable Persistent Room Temperature Phosphorescence Switches through Wavelength-Selective Photoactivation.

Controlling multicolor persistent room-temperature phosphorescence (RTP) through photoirradiation holds fundamental significance but remains a significant challenge. In this study, we engineered a wavelength-selective photoresponsive system utilizing the Förster resonance energy transfer strategy. This system integrates a photoactivated long-lived luminescent material as the energy donor with a fluorescent photoswitch as the energy acceptor, facilitating programmable persistent luminescence switches. Distinct afterglow color states, such as initial nonemissive, green, yellow, and orange, were achieved through irradiation at 400 nm, 365 nm, and 254 nm, respectively. Based on this capability, we established an interacting network for multistate afterglow color switching among these four emissive states. In addition, we demonstrate the potential of this wavelength-selective photoresponsive system in the photo-controlled rewritable printing of multicolor afterglow images on a single thin film. This work represents a substantial step towards the fabrication of sophisticated wavelength-selective photoresponsive systems, potentially revolutionizing applications in optical data storage, security labeling, and smart displays by enabling precise control over photoresponsive behaviors under various photoirradiation wavelengths.

A limit state approach for considering greenhouse gas emissions in the structural design of buildings: Environmental Impact Limit State (EILS)

Recent reports underscore the growing significance of embodied greenhouse gas emissions in the building industry, necessitating sustainable structural designs to combat climate change. However, the current building and structural design codes require satisfying Ultimate and Serviceability Limit States (ULS and SLS) without setting limitations on embodied emissions in the design process of structural members. Thus, this study proposes an Environmental Impact Limit State (EILS), specifying allowable and design emissions for structural components, to be used alongside ULS and SLS. The EILS combines nominal emission intensities from parametric analysis with fuzzy-logic-based uncertainty factors, enabling standardized consideration of environmental impacts in sizing structural elements. The EILS calibration is demonstrated for flat slab and shear wall systems following Canadian codes. The calibration involved an extensive parametric study (450, 975, and 2160 configurations for flat slabs, columns, and shear walls) to evaluate the impact of design and loading parameters. A detailed numerical example is presented to showcase the incorporation of EILS in the design process, achieving emission reduction on magnitude of 25 % compared to non-EILS design process.