Steady-state Lifetime Research Articles

Multispectroscopic and Theoretical Investigation on the Binding Interaction of a Neurodegenerative Drug, Lobeline with Human Serum Albumin: Perturbation in Protein Conformation and Hydrophobic-Hydrophilic Surface.

Lobeline (LOB), a naturally occurring alkaloid, has a broad spectrum of pharmacological activities and therapeutic potential, including applications in central nervous system disorders, drug misuse, multidrug resistance, smoking cessation, depression, and epilepsy. LOB represents a promising compound for developing treatments in various medical fields. However, despite extensive pharmacological profiling, the biophysical interaction between the LOB and proteins remains largely unexplored. In the current article, a range of complementary photophysical and cheminformatics methodologies were applied to study the interaction mechanism between LOB and the carrier protein HSA. Steady-state fluorescence and fluorescence lifetime experiments confirmed the static-quenching mechanisms in the HSA-LOB system. "K" (binding constant) of the HSA-LOB system was determined to be 105 M-1, with a single preferable binding site in HSA. The forces governing the HSA-LOB stable complex were analyzed by thermodynamic parameters and electrostatic contribution. The research also investigated how various metal ions affect complex binding. Site-specific binding studies depict Site I as probable binding in HSA by LOB. We conducted synchronous fluorescence, 3D fluorescence, and circular dichroism studies to explore the structural alteration occurring in the microenvironment of amino acids. To understand the robustness of the HSA-LOB complex, we used theoretical approaches, including molecular docking and MD simulations, and analyzed the principal component analysis and free energy landscape. These comprehensive studies of the structural features of biomolecules in ligand binding are of paramount importance for designing targeted drugs and delivery systems.

Impact of Ionic Liquids on the Physicochemical Behavior of Vesicles.

The effects of two ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) and 1-butyl-1-methyl pyrrolidinium tetrafluoroborate ([bmp]BF4), on a mixture of phospholipids (PLs) 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC), 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), and 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG) (6:3:1, M/M/M, 70% PL) in combination with 30 mol % cholesterol (CHOL) were investigated in the form of a solvent-spread monolayer and bilayer (vesicle). Surface pressure (π)-area (A) isotherm studies, using a Langmuir surface balance, revealed the formation of an expanded monolayer, while the cationic moiety of the IL molecules could electrostatically and hydrophobically bind to the PLs on the palisade layer. Turbidity, dynamic light scattering (size, ζ-potential, and polydispersity index), electron microscopy, small-angle X-ray/neutron scattering, fluorescence spectroscopy, and differential scanning calorimetric studies were carried out to evaluate the effects of IL on the structural organization of bilayer in the vesicles. The ILs could induce vesicle aggregation by acting as a "glue" at lower concentrations (<1.5 mM), while at higher concentrations, the ILs disrupt the bilayer structure. Besides, ILs could result in the thinning of the bilayer, evidenced from the scattering studies. Steady-state fluorescence anisotropy and lifetime studies suggest asymmetric insertion of ILs into the lipid bilayer. MTT assay using human blood lymphocytes indicates the safe application of vesicles in the presence of ILs, with a minimal toxicity of up to 2.5 mM IL in the dispersion. These results are proposed to have applications in the field of drug delivery systems with benign environmental impact.

Mechanistic Insights into Cellular and Molecular Targets of Zinc Oxide Quantum Dots (ZnO QDs) in Fungal Pathogen, Candida albicans: One Drug Multi-Targeted Therapeutic Approach.

Rationally designed multitargeted drugs, known as network therapeutics/multimodal drugs, have emerged as versatile therapeutic solutions to combat drug-resistant microbes. Here, we report novel mechanistic insights into cellular and molecular targets of ZnO quantum dots (QDs) against Candida albicans, a representative of fungal pathogens. Stable, monodispersed 4-6 nm ZnO QDs were synthesized using a wet chemical route, which exhibited dose-dependent inhibition on the growth dynamics of Candida. Treatment with 200 μg/mL ZnO QDs revealed an aberrant morphology and a disrupted cellular ultrastructure in electron microscopy and led to a 23% reduction in ergosterol content and a 53% increase in intracellular reactive oxygen species. Significant increase in steady-state fluorescence polarization and fluorescence lifetime decay of membrane probe 1,6-diphenyl-1,3,5-hexatriene (DPH) in treated cells, respectively, implied reduction in membrane fluidity and enhanced microviscosity. The observed reduction in passive diffusion of fluorescent Rhodamine 6G across the membrane validated the intricate relationship between ergosterol, membrane fluidity, and microviscosity. An inverse relationship existing between ergosterol biosynthetic genes, ERG11 and ERG3 in treated cells, related well with displayed higher susceptibilities. Furthermore, treated cells exhibited impaired functionality and downregulation of ABC drug efflux pumps. Multiple cellular targets of ZnO QDs in Candida were validated by in silico molecular docking. Thus, targeting ERG11, ERG3, and ABC drug efflux pumps might emerge as a versatile, nano-ZnO-based strategy in fungal therapeutics to address the challenges of drug resistance.

Charge transfer dynamics in graphene quantum dot-porphyrin derivative nanohybrids appraised via experimental and theoretical calculations

This article is designed to unveil the electronic and spectroscopic property changes of electron withdrawing/releasing group substituted porphyrins, in porphyrin-graphene quantum dot nanohybrids via experimental and computational calculations. Herein, amino, methyl, fluoro & nitro derivatives of meso substituted Tetraphenylporphyrin referred as TAPP, TMPP, TFPP & TNPP respectively, are synthesized from the corresponding benzaldehydes. Charge transfer dynamics of their nanohybrid systems with graphene quantum dots are investigated by electronic spectroscopy, steady state fluorescence and lifetime decay analysis. Negative Gibb's free energy change and dynamic quenching constants stipulate a photoinduced electron transfer with dynamic quenching mechanism within the nanohybrids under scrutiny. Further the computational calculations with the aid of optimized geometries, scatter plots and energy decomposition analysis reflect the same experimental observations. Both experimental and computational studies show that the electron withdrawing group substituted porphyrins have higher interaction with GQD than the electron releasing group substituted porphyrins.

Doping Ferrocene-Based Conjugated Microporous Polymers with 7,7,8,8-Tetracyanoquinodimethane for Efficient Photocatalytic CO2 Reduction.

The design and synthesis of organic photocatalysts remain a great challenge due to their strict structural constraints. However, this could be mitigated by achieving structural flexibility by constructing permanent porosity into the materials. Conjugated microporous polymers (CMPs) are an emerging class of porous materials with an amorphous, three-dimensional network structure, which makes it possible to integrate the elaborate functional groups to enhance photocatalytic performance. Here, we report the synthesis of a novel CMP, named TAPFc-TFPPy-CMP, constructed by 1,1'3,3'-tetra(4-aminophenyl)ferrocene (TAPFc) and 1,3,6,8-tetrakis(4-formylphenyl)pyrene (TFPPy) monomers. The integration of the p-type dopant 7,7,8,8-tetracyanoquinodimethane (TCNQ) into the TAPFc-TFPPy-CMP improved the light adsorption performance, leading to a decrease in the optical bandgap from 2.00 to 1.43 eV. The doped CMP (TCNQ@TAPFc-TFPPy-CMP) exhibited promising catalytic activity in photocatalytic CO2 reduction under visible light, yielding 546.8 μmol g-1 h-1 of CO with a selectivity of 96% and 5.2 μmol g-1 h-1 of CH4. This represented an 80% increase in the CO yield compared to the maternal TAPFc-TFPPy-CMP. The steady-state photoluminescence (PL) and fluorescence lifetime (FL) measurements reveal faster carrier separation and transport after the doping. This study provides guidance for the development of organic photocatalysts for the utilization of renewable energy.

Recombination and Trapping of Excess Carriers in n-InSb

The effect of trapping on the transient and steady-state lifetimes of excess carriers is investigated in InSb of n-type conductivity. Photoconductive decay and direct current measurements are used to characterize the starting material and infrared photodiodes. The large difference between the transient and steady-state lifetimes is explained by the trapping of minority carriers at the acceptor centers within the two-level recombination model. The recombination parameters of the traps are estimated.

Characterization of the Binding Properties of Ten Aptamers Using the Intrinsic Fluorescence of Oxytetracycline.

Tetracyclines are a class of commonly used four-ringed antibiotics. A series of DNA aptamers were recently obtained using the capture-SELEX (systematic evolution of ligands by exponential enrichment) method to bind to oxytetracycline, and one of the aptamers can bind to a few other tetracycline antibiotics as well. Upon binding to the aptamers, the intrinsic fluorescence of tetracycline antibiotics can be enhanced. At least 10 different DNA aptamers were isolated from the previous selection experiment. In this work, a systematic characterization of these ten aptamers was performed. Each of these aptamers shows a different degree of fluorescence enhancement ranging from around 1-fold to over 20-fold. Fluorescence enhancement was boosted in the presence of Mg2+. Isothermal titration calorimetry (ITC) studies were done and showed a great variety in dissociation constant (Kd) from 62 nM to 1.6 μM. Steady-state fluorescence spectroscopy and fluorescence lifetime studies showed a correlation between fluorescence lifetime and degree of fluorescence enhancement. A few aptamers showed slow binding kinetics, although no correlation was found between the kinetics of fluorescence change and degree of fluorescence enhancement. This is the first study of ten different aptamers for the same target, providing fundamental insights into aptamer binding and bioanalytical applications.

Measurement report: Atmospheric nitrate radical chemistry in the South China Sea influenced by the urban outflow of the Pearl River Delta

Abstract. The nitrate radical (NO3) is a critical nocturnal atmospheric oxidant in the troposphere, which widely affects the fate of air pollutants and regulates air quality. Many previous works have reported the chemistry of NO3 in inland regions of China, while fewer studies target marine regions. Here, we present a field measurement of the NO3 reservoir, dinitrogen pentoxide (N2O5), and related species at a typical marine site (Da Wan Shan Island) located in the South China Sea in the winter of 2021. Two patterns of air masses were captured during the campaign, including the dominant airmass from inland China (IAM) with a percentage of ∼ 84 %, and the airmass from eastern coastal areas (CAM) with ∼ 16 %. During the IAM period, the NO3 production rate reached 1.6 ± 0.9 ppbv h−1 due to the transportation of the polluted urban plume with high NOx and O3. The average nocturnal N2O5 and the calculated NO3 mixing ratios were 119.5 ± 128.6 and 9.9 ± 12.5 pptv, respectively, and the steady-state lifetime of NO3 was 0.5 ± 0.7 min on average, indicating intensive nighttime chemistry and rapid NO3 loss at this site. By examining the reaction of NO3 with volatile organic compounds (VOCs) and N2O5 heterogeneous hydrolysis, we revealed that these two reaction pathways were not responsible for the NO3 loss (&lt; 20 %) since the NO3 reactivity (k(NO3)) towards VOCs was small (5.2×10-3 s−1) and the aerosol loading was low. Instead, NO was proposed to significantly contribute to nocturnal NO3 loss at this site, despite the nocturnal NO concentration always below the parts per billion by volume level and near the instrument detection limit. This might be from the local soil emission or something else. We infer that the nocturnal chemical NO3 reactions would be largely enhanced once without NO emission in the open ocean after the air mass passes through this site, thus highlighting the strong influences of the urban outflow to the downwind marine areas in terms of nighttime chemistry. During the CAM period, nocturnal ozone was higher, while NOx was much lower. The NO3 production was still very fast, with a rate of 1.2 ppbv h−1. With the absence of N2O5 measurement in this period, the NO3 reactivity towards VOCs and N2O5 uptake were calculated to assess NO3 loss processes. We showed that the average k(NO3) from VOCs (56.5 %, 2.6 ± 0.9 × 10−3 s−1) was higher than that from N2O5 uptake (43.5 %, 2.0 ± 1.5 × 10−3 s−1) during the CAM period, indicating a longer NO3 / N2O5 lifetime than that during IAM period. This study improves the understanding of the nocturnal NO3 budget and environmental impacts with the interaction of anthropogenic and natural activities in marine regions.

Minimizing Interfacial Recombination in 1.8eVTriple-Halide Perovskites for 27.5% Efficient All-Perovskite Tandems.

All-perovskite tandem solar cells show great potential to enable the highest performance at reasonable costs for a viable market entry in the near future. In particular, wide-bandgap (WBG) perovskites with higher open-circuit voltage (VOC ) are essential to further improve the tandem solar cells' performance. Here, a new 1.8eV bandgap triple-halide perovskite composition in conjunction with a piperazinium iodide (PI) surface treatment is developed. With structural analysis, it is found that the PI modifies the surface through a reduction of excess lead iodide in the perovskite and additionally penetrates the bulk. Constant light-induced magneto-transport measurements are applied to separately resolve charge carrier properties of electrons and holes. These measurements reveal a reduced deep trap state density, and improved steady-state carrier lifetime (factor 2.6) and diffusion lengths (factor 1.6). As a result, WBG PSCs achieve 1.36V VOC , reaching 90% of the radiative limit. Combined with a 1.26eV narrow bandgap (NBG) perovskite with a rubidium iodide additive, this enables a tandem cell with a certified scan efficiency of 27.5%.

Achieving high-quality silver sintered joint for highly-reliable schottky barrier diodes via pressureless method

The fabrication of silver joints was done using the pressureless sintering technology to suit the demand of high-reliability schottky barrier diodes (SBD). Porosity of 10.6% and shear strength of 39.6 MPa were reached under the optimized parameters of 290°C sintering temperature and 40 min residence time. The sintered joint demonstrated good mechanical/thermal/electrical performance in the ultimate reliability assessment testing, including the temperature cycling test, second sintering test, steady-state lifetime test, and intermittent lifetime test. This study demonstrated the viability of pressureless sintering of silver joints with good high-temperature reliability, which has significant application potential for aeronautical high-reliability power electronics.

Sensing of picric acid using an AIEE active “Turn Off” fluorescent probe derived from hydroxy naphthaldehyde and benzyloxy benzaldehyde

A novel Schiff base with AIEE characteristics has been developed and used as a chemosensor for picric acid in aqueous media. The Schiff base 1-((E)-((E)-(4-(benzyloxy) benzylidene) hydrazono) methyl) naphthalen-2-ol [BBHN] with strong fluorescence emission was obtained by the simple condensation of 1-(hydrazonomethyl)naphthan-2-ol and 4-benzoxy benzaldehyde. The characterization of BBHN was done using Fourier Transfer Infra-Red, UV–visible, Magnetic Resonance (1H and 13C) spectroscopy, and HRMS. The sensing behaviour of BBHN aggregates towards nitro explosive was then investigated. The aggregates of BBHN showed a quick, highly selective, and sensitive fluorescence ‘Turn Off’ response towards picric acid (PA) in an aqueous medium among various other nitroaromatics. The limit of detection was 4.04 µM with 2.03 × 106 M−1 as the quenching constant. The fluorescence “Turn Off” response in the presence of PA is mainly due to π-π interactions, and non-covalent hydrogen bonding interactions. Moreover, steady-state fluorescence lifetime measurement and Stern − Volmer plots reveal that the fluorescence quenching followed mixed quenching strategies.

Fluorescence Resonance Energy Transfer Properties and Auger Recombination Suppression in Supraparticles Self-Assembled from Colloidal Quantum Dots

Colloid quantum dots (CQDs) are recognized as an ideal material for applications in next-generation optoelectronic devices, owing to their unique structures, outstanding optical properties, and low-cost preparation processes. However, monodisperse CQDs cannot meet the requirements of stability and collective properties for device applications. Therefore, it is urgent to build stable 3D multiparticle systems with collective physical and optical properties, which is still a great challenge for nanoscience. Herein, we developed a modified microemulsion template method to synthesize quantum dot supraparticles (QD-SPs) with regular shapes and a high packing density, which is an excellent research platform for ultrafast optical properties of composite systems. The redshift of the steady-state fluorescence spectra of QD-SPs compared to CQD solutions indicates that fluorescence resonance energy transfer (FRET) occurred between the CQDs. Moreover, we investigated the dynamic processes of energy transfer in QD-SPs by time-resolved ultrafast fluorescence spectroscopy. The dynamic redshift and lifetime changes of the spectra further verified the existence of rapid energy transfer between CQDs with different exciton energies. In addition, compared with CQD solutions, the steady-state fluorescence lifetime of SPs increased and the fluorescence intensity decreased slowly with increasing temperature, which indicates that the SP structure suppressed the Auger recombination of CQDs. Our results provide a practical approach to enhance the coupling and luminescence stability of CQDs, which may enable new physical phenomena and improve the performance of optoelectronic devices.

Charge Transfer in Amine-Free CsPbBr3 Perovskite Nanocrystals and Organic Hole-Acceptor Hybrid Structures

Outstanding optoelectronic properties of cesium lead bromide (CsPbBr3) perovskite nanocrystals (PNCs) are recognized in various photonic devices. The surface chemistry of PNCs determines the excited states of PNCs, and their interactions with charge drive redox-active molecules. Here, we have investigated the potential difference between the surface modification of different CsPbBr3-based PNCs (amine-free and amine-based) with the hole-accepting organic molecule, i.e., 7,7-diethyl-5,7-dihydroindeno[2,1-b] carbazole (SPS-IND-Cbz). We have evaluated photoinduced hole transfer (PHT) with the steady-state photoluminescence and lifetime decay curves. Excitingly, the resulting PHT in amine-free CsPbBr3 PNC was nearly twice that of the amine-based CsPbBr3 PNC. Further, we have studied the photocurrent density of amine-free CsPbBr3 PNCs in the newly introduced organic molecule (SPS-IND-Cbz), enhancing the photocurrent responsivity, which could open a promising perspective for implementing these fascinating materials in various photonic strategies.

Steady-state and fluorescence lifetime quenching of self-assembled diphenylalanine/coumarin nanostructures as a method to determine dissolved O2 in water

A fluorescent system formed by the combination of coumarin derivative and self-assembled peptide nanostructures was used as sensing system to determine dissolved oxygen (O2) in water samples. Detection was based on the sensing system fluorescence quenching by O2, measured by steady-state and time-resolved fluorescence spectroscopy and Stern-Volmer plot to correlate fluorescence intensity to O2 concentration in the samples. Also, fluorescence lifetime decays informed about the mechanisms in which the quenching is occurring, indicating that the sensing system is highly sensitive and selective to O2, since quenching occurs by a non-radiative energy transfer from electronic excited singlet states of the system to the O2 molecule. This process was evidenced by the system fluorescence lifetime decrease, yielding Singlet O2 as indicative that this system can also find other technological applications.

Water-induced fluorescence turn-on imidazole derivative and its interaction with bovine serum albumin

A new trityl imidazole derivative L was synthesized in one-step by reacting 1H-imidazole with triphenylmethyl chloride. The receptor L was applied for the detection of trace amounts of water in DMSO. The weakly emissive L in DMSO showed a significant fluorescence enhancement upon the addition of water due to the suppression of the photo-induced electron transfer process and aggregation-induced emission. The sensitivity of L to detect water in DMSO was estimated as 0.002 wt%. Further, the protein-ligand binding interaction between L and BSA was explored by steady-state fluorescence, fluorescence anisotropy and fluorescence lifetime under physiological conditions at pH 7. The formation of the BSA-L complex quenched the fluorescence emission of BSA. The molecular docking analysis was performed to establish the binding mode and stability of the BSA-L complex. The multiple non-covalent interactions occurred between the residues of BSA and the receptor L stabilized the BSA-L complex.

Exploring binding chemistry of alkali/alkaline earth cations in solution through modulation of intramolecular charge-transfer in an excited ambidentate organic fluorophore.

Studying the metal-ligand monoligation of alkali/alkaline earth metals (AMs) in solution represents a significant challenge due to the low stabilization of their complexes and the absence of an effective strategy to identify this type of weak binding. Herein, we show that the modulation of the intramolecular charge-transfer (ICT) in an excited ambidentate organic fluorophore is a convenient strategy to characterize the binding chemistry of AM cations in solution through simple steady-state fluorescence and fluorescence lifetime measurements. The key points of the fluorophore as a metal-binding probe were the location of diverse coordination functionalities with different binding abilities (ionic-, pseudo-covalent- and non-covalent-probes) along the donor-acceptor (D-A) chain and the occurrence of an intramolecular charge-transfer (ICT) mechanism upon excitation. The binding of these functionalities with AM-cations generated selective and specific fluorescence responses, which were quantifiable and allowed us to recognize the primary, secondary and tertiary interactions for all the AM cations in the solution. The relative binding affinities for each one of the functionalities with AM cations was estimated, and a general and consistent perspective of the binding of AMs as a function of their location in the Periodic Table, hardness property and ionic radius was established. The binding preferences of the AM cations were supported by DFT calculations. Our strategy allowed us to validate the binding dynamics of AMs in solution for three types of key ligations, which opens a new perspective to recognize weak intermolecular interactions derived from acidic species and rationally design selective AM-cation probes using an ICT-based ambidentate organic fluorophore.

Photoluminescent Polymer Aerogels with R, G and B Emission.

In this work, three new polymer aerogels based on 2-hydroxy ethyl methacrylate (HEMA) complexes with Eu(III), Tb(III) and La(III) are prepared and investigated. The polymer aerogels present strong photoluminescence with emissions located in the red, green and blue regions of the visible spectrum. Depending on the water content used during the preparation path, the consistency of the photoluminescent aerogels varies from rigid, regularly shaped monoliths to a flexible, fibrous material with very low density. The morpho-structural investigation was performed by FT-IR, XPS and SEM. Thermal behavior was also evaluated, while steady-state fluorescence spectroscopy, absolute PLQY and lifetime were used for the investigation of their luminescent properties. The impressive photoluminescent emission located in the red, green and blue areas of the visible spectrum is preserved irrespective of the selected porosity. Their photo-emissive properties, tunable porosity and the convenience of the preparation path could be some arguments for applications as photonic conversion mediums in special-purpose optoelectronic devices or sensors.

A comprehensive insight into the effects of punicalagin on pepsin: Multispectroscopy and simulations methods

Punicalagin has been attracted much attention owing to its biological activity of regulating blood glucose and potential as a health benefits. Herein, the binding behavior of punicalagin with pepsin were investigated by spectrofluorometric, UV–Vis spectrophotometric, synchronous fluorescence, three-dimensional (3-D) fluorescence, circular dichroism (CD), UV–Vis, Fourier transform infrared (FT-IR), docking examinations and molecular dynamics simulation. Fluorescence spectroscopy reveals that punicalagin spontaneously binds to pepsin and quenches the intrinsic fluorescence of pepsin. According to the results of steady-state fluorescence and fluorescence lifetime, the quenching mechanism of punicalagin and pepsin was static quenching. Synchronous fluorescence spectroscopy, 3-D fluorescence, CD, UV–Vis and FT-IR demonstrated that it induced conformational alterations of pepsin in the presence of punicalagin. Complementary molecular docking and dynamics simulations elucidated that the binding of pepsin and punicalagin occurred via establishment of hydrogen-bonding and Van der Waals interactions. This work provided some important information for further research on punicalagin-proteases interactions, which contributed to the activity and binding mechanism of punicalagin and pepsin in future.

A convenient method for assessing steady-state carrier density and lifetime in solar cell materials using pulse excitation measurements.

We describe the relation of the carrier lifetime of a light-absorber material determined with pulse-excitation time-resolved techniques to the steady-state carrier density and lifetime in a solar cell under continuous-wave excitation. Our approach constitutes a simple experimental examination of the excitation-fluence-dependent carrier lifetime of absorber materials. It provides the steady-state carrier density and lifetime under 1-sun solar illumination for metal halide perovskite solar cells. The determination of the steady-state carrier responses allows the clarification of optical and photovoltaic properties under 1-sun illumination and thus the identification of loss mechanisms in device performance. Model calculations are also provided to show how the carrier lifetime governs the luminescence quantum yields and open-circuit voltages. The calculations quantify a scaling law between a monomolecular recombination lifetime and an open-circuit voltage as a result of a combination of two density-dependent effects.

Reactivity and Loss Mechanisms of NO3 and N2O5 at a Rural Site on the North China Plain

NO3, NO2, O3, and relevant parameters were measured at a rural site on the North China Plain during June 2014. During the campaign, the average concentrations of NO3 and N2O5 were 4.8 ± 3.3 pptv and 30.5 ± 35.4 pptv, respectively. The average NO3 production rate was 1.03 ± 0.48 ppbvh−1, and the steady-state lifetimes of NO3 and N2O5 were 26 s and 162 s, respectively, indicating that the NOx chemistry in the rural site during summer was active. The uptake coefficient range of N2O5 was 0.023 to 0.118, with an average value of 0.062 ± 0.035. Meanwhile, the fitting for kNO3 was 0.013 ± 0.016 s−1, corresponding to the shorter NO3 lifetime below 1 min. The results show that the indirect loss pathways caused by the heterogonous uptake of N2O5 contributed 64–90% of the overall NO3 loss, with an average of 81%, suggesting that the N2O5 heterogeneous reaction dominated the nocturnal NOx loss over this region.