Experimental realization of multiple frequency photoassociation in an optical dipole trap.

The generation of cold molecules is an important topic in the field of cold atoms and molecules and has received relevant advanced research attention in ultracold chemistry, quantum computation, and quantum metrology. With a high atomic phase space density, optical dipole traps have been widely used to prepare, trap, and study cold molecules. In this work, Rb2 molecules were photoassociated in a magneto-optical trap to obtain a precise rovibrational spectrum, which provided accurate numerical references for the realization of multiple frequency photoassociation. By meeting the harsh requirements of photoassociation in optical dipole traps, the cold molecule photoassociation process was well explored, and different photoassociation resonances were simultaneously addressed in a single optical dipole trap. This method can be universally extended to simultaneously photoassociate cold molecules with different internal states or atomic species in a single optical dipole trap, thus advancing generous cold molecule studies such as cold molecule collision dynamics.

Bird diversity in semi-humid evergreen broad-leaved forest patches on the central Yunnan Plateau, Southwest China.

We assessed the diversity, composition, and distribution of bird species in patches of semi-humid evergreen broad-leaved forest by selecting eight natural forest communities in the central Yunnan Plateau, which is a representative distribution area of semi-humid broad-leaved evergreen forest. Field observations were conducted from April to August 2023 by the sample line and sample point method, and eight survey routes of 3-4 km in length were established. The results showed that 1) A total of 1286 birds were recorded, belonging to 102 species in 7 orders and 30 families. The three most abundant families were Muscicapidae (14 species), Leiothrichidae (9 species), and Phylloscopidae (7 species); 2) Species of Oriental origin, Palaearctic origin, and widespread species accounted for 81.4%, 4.9%, and 13.7% of observations, respectively; 3) The average number of bird species surveyed in forest patches was 32.0±3.5; the Shannon index of birds was lower in secondary, semi-humid evergreen broad-leaved forests (1.536±0.110) than in primary forest communities (2.037±0.100); 4) Species composition exhibited considerable variation between patches, with the presence of dominant and common species, and the difference in rare species; 5) Considering the ecological groups of birds based on diet, invertebrate-eating and omnivorous birds, herbivorous birds, and carnivorous birds accounted for 84.3%, 11.8%, and 3.9%, respectively. The coexistence of birds with similar diets was maintained by diluting interspecific competition, mainly through partitioning of the vertical feeding space. For the conservation of bird species diversity and rare species, all patches of native semi-humid evergreenbroad-leaved forest are of conservation value.

Boosting K+-ionic Conductivity of Layered Oxides via Regulating P2/P3 Heterogeneity and Reciprocity for Room-temperature Quasi-solid-state Potassium Metal Batteries.

Solid-state potassium metal batteries are promising candidates for grid-scale energy storage due to their low cost, high energy density and inherent safety. However, solid state K-ion conductors struggle with poor ionic conductivity due to the large ionic radius of K+-ions. Herein, we report precise regulation of phase heterogeneity and reciprocity of the P2/P3-symbiosis K0.62Mg0.54Sb0.46O2 solid electrolyte (SE) for boosting a high ionic conductivity of 1.6×10-4 S cm-1 at 25 °C. The bulk ionic conducting mechanism is explored by elucidating the effect of atomic stacking mode within the layered framework on K+-ion migration barriers. For ion diffusion at grain boundaries, the P2/P3 biphasic symbiosis property assists in tunning the SE microstructure, which crystallizes in rod-like particles with lengths of tens of micrometers facilitating long-distance ion transport and significantly decreasing grain boundary resistance. Potassium metal symmetric cells using the modified SE deliver excellent cycling life over 300 h at 0.1 mA cm-2 and a high critical current density of 0.68 mA cm-2. The quasi-solid-state potassium metal batteries (QSSKBs) coupled with two kinds of layered oxide cathodes demonstrate remarkable stability over 300 cycles, outperforming the liquid electrolyte counterparts. The QSSKB system provides a promising strategy for high-efficiency, safe, and durable large-scale energy storage.

Recent research progress on tumour-specific responsive hydrogels.

Most existing hydrogels, even recently developed injectable hydrogels that undergo a reversible sol-gel phase transition in response to external stimuli, are designed to gel immediately before or after implantation/injection to prevent the free diffusion of materials and drugs; however, the property of immediate gelation leads to a very weak tumour-targeting ability, limiting their application in anticancer therapy. Therefore, the development of tumour-specific responsive hydrogels for anticancer therapy is imperative because tumour-specific responses improve their tumour-targeting efficacy, increase therapeutic effects, and decrease toxicity and side effects. In this review, we introduce the following three types of tumour-responsive hydrogels: (1) hydrogels that gel specifically at the tumour site; (2) hydrogels that decompose specifically at the tumour site; and (3) hydrogels that react specifically with tumours. For each type, their compositions, the mechanisms of tumour-specific responsiveness and their applications in anticancer treatment are comprehensively discussed.

Identification of ACAA1 and HADHB as potential prognostic biomarkers based on a novel fatty acid oxidation-related gene model in head and neck squamous cell carcinoma: A retrospective study.

OBJECTIVES: To investigate the importance of fatty acid oxidation (FAO)-related genes in predicting the progression and prognosis of head and neck squamous cell carcinoma (HNSCC). METHODS: The FAO-related gene prognostic model was established employing Cox regression analyses, during which accuracy and sensitivity of the gene model were evaluated in The Cancer Genome Atlas (TCGA) internal testing and Gene Expression Omnibus (GEO) external validation cohorts. Ultimately, hub genes were identified among 13 model genes using STRING and Cytoscape, with preliminary validation carried out through immunohistochemistry. RESULTS: The model, which comprised 13 genes (ABCD2, ACAA1, ACACB, AKT1, CNR1, CPT1C, CROT, ECHDC2, ETFA, HADHB, IRS2, LONP2, and SLC25A17), was established. On the basis of the median risk score, the two cohorts were grouped into low-and high-risk groups in the subsequent test and validation, and the former exhibited significantly higher survival rates than the latter. Nomograms were established based on prognostic factors, including stage and risk score, and individualized for the prediction of HNSCC patients. Ultimately, immunohistochemical staining showed that ACAA1 and HADHB were significantly under-expressed in HNSCC, with a favorable prognosis associated with low HADHB and high ACAA1. CONCLUSIONS: The gene prognostic model has illustrated promising capability in predicting the prognosis, and ACAA1 and HADHB might serve as potential therapeutic biomarkers for HNSCC patients.

Developing a novel lithium-ion battery anode material via thiol functionalization of diatom frustules plus Ag modification.

The biosilicification of diatoms allows for the customization of the synthesis of functionalized diatom frustules. The S active sites (-SH) on diatom frustules were created by adding the organic silicon sources tetramethoxysilane (TMOS) and (3-mercaptopropyl)trimethoxysilane (MPTMS). The mechanisms of adsorption-reduction and the indirect effects of S active sites on electrochemical performance were declared. The DBS@C-Ag-3 anode material sourced from the cultivation condition with a silicon source of TMOS:MPTMS = 3:1 shows the best comprehensive performance and delivers a discharge capacity of ∼660 mAh·g-1 after 1000 cycles at 1 A·g-1. The electrochemical performance of DBS@C-Ag anode materials is also found to be dominated by structure at high temperatures and conductivity at low temperatures. Such a diatom frustule structure with sulfhydryl functionalization is promising for anode materials, and it suggests a biological strategy for creating other electrode materials by modifying them with metals to improve electrochemical performances.

Symmetry Breaking and Spin-Orbit Coupling for Individual Vacancy-Induced In-Gap States in MoS2 Monolayers.

Spins confined to point defects in atomically thin semiconductors constitute well-defined atomic-scale quantum systems that are being explored as single-photon emitters and spin qubits. Here, we investigate the in-gap electronic structure of individual sulfur vacancies in molybdenum disulfide (MoS2) monolayers using resonant tunneling scanning probe spectroscopy in the Coulomb blockade regime. Spectroscopic mapping of defect wave functions reveals an interplay of local symmetry breaking by a charge-state-dependent Jahn-Teller lattice distortion that, when combined with strong (≃100 meV) spin-orbit coupling, leads to a locking of an unpaired spin-1/2 magnetic moment to the lattice at low temperature, susceptible to lattice strain. Our results provide new insights into the spin and electronic structure of vacancy-induced in-gap states toward their application as electrically and optically addressable quantum systems.

The direct transfer approach for transcellular drug delivery.

A promising paradigm for drug administration that has garnered increasing attention in recent years is the direct transfer (DT) of nanoparticles for transcellular drug delivery. DT requires direct cell-cell contact and facilitates unidirectional and bidirectional matter exchange between neighboring cells. Consequently, DT enables fast and deep penetration of drugs into the targeted tissues. This comprehensive review discusses the direct transfer concept, which can be delineated into the following three distinct modalities: membrane contact-direct transfer, gap junction-mediated direct transfer (GJ-DT), and tunneling nanotubes-mediated direct transfer (TNTs-DT). Further, the intercellular structures for each modality of direct transfer and their respective merits and demerits are summarized. The review also discusses the recent progress on the drugs or drug delivery systems that could activate DT.

Clinicopathological and prognostic significance of Ephrin A3 in bladder urothelial carcinoma.

Ephrin A3 (EFNA3) is a member of the Eph/ephrin tyrosine kinase family, which is associated with multiple signaling pathways involved in cell growth and tumor cell metastasis. Aberrant regulation of EFNA3 is associated with the occurrence and development of various types of cancer. However, despite the high incidence of EFNA3 upregulation in cancer, studies concerning EFNA3 in urothelial carcinoma have not, to the best of our knowledge, been conducted. In the present study, bioinformatics analyses using data from multiple online databases were performed to confirm the upregulation of EFNA3 in bladder cancer. The co-expression gene set of EFNA3 and enriched signaling pathways were also analyzed. In addition, immunohistochemistry was conducted to detect EFNA3 expression in 491 clinically confirmed bladder urothelial carcinoma samples and 80 non-cancerous bladder tissues. Kaplan-Meier survival analysis, binary logistic regression analysis, and Cox regression analysis were conducted to confirm the validity of EFNA3 in predicting patient prognosis and its significance in clinical pathology. Statistical analysis demonstrated a significant association between EFNA3 expression levels with tumor size, lymph node metastasis, distant metastasis, and pathological grade. In conclusion, high EFNA3 expression may be a potential biomarker that indicates bladder tumor occurrence and patient prognosis.

Near-Unity Emitting, Widely Tailorable, and Stable Exciton Concentrators Built from Doubly Gradient 2D Semiconductor Nanoplatelets.

The strength of electrostatic interactions (EIs) between electrons and holes within semiconductor nanocrystals profoundly affects the performance of their optoelectronic systems, and different optoelectronic devices demand distinct EI strength of the active medium. However, achieving a broad range and fine-tuning of the EI strength for specific optoelectronic applications is a daunting challenge, especially in quasi two-dimensional core-shell semiconductor nanoplatelets (NPLs), as the epitaxial growth of the inorganic shell along the direction of the thickness that solely contributes to the quantum confined effect significantly undermines the strength of the EI. Herein we propose and demonstrate a doubly gradient (DG) core-shell architecture of semiconductor NPLs for on-demand tailoring of the EI strength by controlling the localized exciton concentration via in-plane architectural modulation, demonstrated by a wide tuning of radiative recombination rate and exciton binding energy. Moreover, these exciton-concentration-engineered DG NPLs also exhibit a near-unity quantum yield, high photo- and thermal stability, and considerably suppressed self-absorption. As proof-of-concept demonstrations, highly efficient color converters and high-performance light-emitting diodes (external quantum efficiency: 16.9%, maximum luminance: 43,000 cd/m2) have been achieved based on the DG NPLs. This work thus provides insights into the development of high-performance colloidal optoelectronic device applications.

Aggregation enhanced FRET: A simple but efficient strategy for the ratiometric detection of uranyl ion.

Uranium is one of the most important radionuclides but could also cause potential health risks to human beings due to its radioactive and chemical toxicity. It is an urgent task to develop a simple but efficient sensing platform for UO22+, the main existing form of uranium in environment. Herein, a rhodamine-functionalized carbon dots (o-CDs-Rho) was synthesized and applied for UO22+ sensing through a simple but novel aggregation-enhanced FRET strategy. The weak FRET efficiency (16.2%) of o-CDs-Rho in dispersed solution is significantly enhanced (>77.2%) after UO22+ triggered aggregation due to the increased number of rhodamine acceptors around each CDs from dispersed 80 to aggregated 2800. This is the first ratiometric fluorescence sensor with an inverse change of fluorescence intensity at dual emission wavelengths under single-wavelength excitation for UO22+. Under optimized experiment conditions, o-CDs-Rho nanosensor shows a low detection limit of 53 nM and excellent selectivity. Meanwhile, the as-prepared nanosensor also shows high reliability and stability. These excellent properties make it successful in detecting uranium content in real samples.

Diatom Frustules Decorated with Co Nanoparticles for the Advanced Anode of Li-Ion Batteries.

Silica is regarded as a promising anode material for lithium-ion batteries (LIBs) because of its high theoretical capacity. However, large volume variation and poor electrical conductivity are limiting factors for the development of SiO2 anode materials. To solve this problem, combining SiO2 with a conductive phase and designing hollow porous structures are effective ways. In this work, The Co(II)-EDTA chelate on the surface of diatom biosilica (DBS) frustules and obtained DBS@C-Co composites decorated with Co nanoparticles by calcination without a reducing atmosphere is first precipitated. The unique three-dimensional structure of diatom frustules provides enough space for the volume change of silica during lithiation/delithiation. Co nanoparticles effectively improve the electrical conductivity and electrochemical activity of silica. Through the synergistic effect of the hollow porous structure, carbon layer and Co nanoparticles, the DBS@C-Co-60 composite delivers a high reversible capacity of >620 mAh g-1 at 100 mA g-1 after 270 cycles. This study provides a new method for the synthesis of metal/silica composites and an opportunity for the development of natural resources as advanced active materials for LIBs.

Continuously and widely tunable frequency-stabilized laser based on an optical frequency comb.

Continuously and widely tunable lasers, actively stabilized on a frequency reference, are broadly employed in atomic, molecular, and optical (AMO) physics. The frequency-stabilized optical frequency comb (OFC) provides a novel optical frequency reference, with a broadband spectrum that meets the requirement of laser frequency stabilization. Therefore, we demonstrate a frequency-stabilized and precisely tunable laser system based on it. In this scheme, the laser frequency locked to the OFC is driven to jump over the ambiguity zones, which blocks the wide tuning of the locked laser, and tuned until the mode hopping happens with the always-activated feedback loop. Meanwhile, we compensate the gap of the frequency jump with a synchronized acoustic optical modulator to ensure the continuity. This scheme is applied to an external cavity diode laser (ECDL), and we achieve tuning at a rate of about 7 GHz/s, with some readily available commercial electronics. Furthermore, we tune the frequency-stabilized laser only with the feedback of diode current, and its average tuning speed can exceed 100 GHz/s. Due to the resource-efficient configuration and the simplicity of completion, this scheme can be referenced and can find wide applications in AMO experiments.

Thermopressure Coupling Effect Mimicking Natural Graphite Formation to Enhance the Storage K-Ion Performance of Carbonaceous Heterostructures.

Borrowing from natural mechanisms for material design can lead to functional mimicry and improvement. Inspired by graphite formation, a thermopressure coupling strategy under micropressure (<400 Pa) is applied to prepare carbon anodes. A thermopressure response is discovered based on the cellulose precursor. Here, homologous graphene quantum dot/hard carbon (GQD/HC) heterostructures are synthesized. Under 181.4 Pa and 1,200 °C, the product shows a capacity of 310 mAh g-1, while the capacity of the direct carbonization product is only 120 mAh g-1. Prominently, the GQD/HC heterostructure displays marked mechanical strength and flexibility. The experimental and theoretical results illustrate the ion and electron transfer, coordination environment, and electronic states in the GQD/HC heterostructure and elaborate on the origin of the enhanced performance. The thermopressure coupling under micropressure mimics graphite formation, but the heterostructure has better properties than traditional carbon materials. Additionally, micropressure injects new vitality into material research.

2D Material Infrared Photonics and Plasmonics.

Two-dimensional (2D) materials including graphene, transition metal dichalcogenides, black phosphorus, MXenes, and semimetals have attracted extensive and widespread interest over the past years for their many intriguing properties and phenomena, underlying physics, and great potential for applications. The vast library of 2D materials and their heterostructures provides a diverse range of electrical, photonic, mechanical, and chemical properties with boundless opportunities for photonics and plasmonic devices. The infrared (IR) regime, with wavelengths across 0.78 µm to 1000 µm, has particular technological significance in industrial, military, commercial, and medical settings while facing challenges especially in the limit of materials. Here, we present a comprehensive review of the varied approaches taken to leverage the properties of the 2D materials for IR applications in photodetection and sensing, light emission and modulation, surface plasmon and phonon polaritons, non-linear optics, and Smith-Purcell radiation, among others. The strategies examined include the growth and processing of 2D materials, the use of various 2D materials like semiconductors, semimetals, Weyl-semimetals and 2D heterostructures or mixed-dimensional hybrid structures, and the engineering of light-matter interactions through nanophotonics, metasurfaces, and 2D polaritons. Finally, we give an outlook on the challenges in realizing high-performance and ambient-stable devices and the prospects for future research and large-scale commercial applications.

Pressure driven rotational isomerism in 2D hybrid perovskites.

Multilayers consisting of alternating soft and hard layers offer enhanced toughness compared to all-hard structures. However, shear instability usually exists in physically sputtered multilayers because of deformation incompatibility among hard and soft layers. Here, we demonstrate that 2D hybrid organic-inorganic perovskites (HOIP) provide an interesting platform to study the stress-strain behavior of hard and soft layers undulating with molecular scale periodicity. We investigate the phonon vibrations and photoluminescence properties of Ruddlesden-Popper perovskites (RPPs) under compression using a diamond anvil cell. The organic spacer due to C4 alkyl chain in RPP buffers compressive stress by tilting (n = 1 RPP) or step-wise rotational isomerism (n = 2 RPP) during compression, where n is the number of inorganic layers. By examining the pressure threshold of the elastic recovery regime across n = 1-4 RPPs, we obtained molecular insights into the relationship between structure and deformation resistance in hybrid organic-inorganic perovskites.

Inorganic frameworks of low-dimensional perovskites dictate the performance and stability of mixed-dimensional perovskite solar cells.

Mixed-dimensional perovskites containing mixtures of organic cations hold great promise to deliver highly stable and efficient solar cells. However, although a plethora of relatively bulky organic cations have been reported for such purposes, a fundamental understanding of the materials' structure, composition, and phase, along with their correlated effects on the corresponding optoelectronic properties and degradation mechanism remains elusive. Herein, we systematically engineer the structures of bulky organic cations to template low-dimensional perovskites with contrasting inorganic framework dimensionality, connectivity, and coordination deformation. By combining X-ray single-crystal structural analysis with depth-profiling XPS, solid-state NMR, and femtosecond transient absorption, it is revealed that not all low-dimensional species work equally well as dopants. Instead, it was found that inorganic architectures with lesser structural distortion tend to yield less disordered energetic and defect landscapes in the resulting mixed-dimensional perovskites, augmented in materials with a longer photoluminescence (PL) lifetime, higher PL quantum yield (up to 11%), improved solar cell performance and enhanced thermal stability (T80 up to 1000 h, unencapsulated). Our study highlights the importance of designing templating organic cations that yield low-dimensional materials with much less structural distortion profiles to be used as additives in stable and efficient perovskite solar cells.

Reversible Photochromism in ⟨110⟩ Oriented Layered Halide Perovskite.

Extending halide perovskites' optoelectronic properties to stimuli-responsive chromism enables switchable optoelectronics, information display, and smart window applications. Here, we demonstrate a band gap tunability (chromism) via crystal structure transformation from three-dimensional FAPbBr3 to a ⟨110⟩ oriented FAn+2PbnBr3n+2 structure using a mono-halide/cation composition (FA/Pb) tuning. Furthermore, we illustrate reversible photochromism in halide perovskite by modulating the intermediate n phase in the FAn+2PbnBr3n+2 structure, enabling greater control of the optical band gap and luminescence of a ⟨110⟩ oriented mono-halide/cation perovskite. Proton transfer reaction-mass spectroscopy carried out to precisely quantify the decomposition product reveals that the organic solvent in the film is a key contributor to the structural transformation and, therefore, the chromism in the ⟨110⟩ structure. These intermediate n phases (2 ≤ n ≤ ∞) stabilize in metastable states in the FAn+2PbnBr3n+2 system, which is accessible via strain or optical or thermal input. The structure reversibility in the ⟨110⟩ perovskite allowed us to demonstrate a class of photochromic sensors capable of self-adaptation to lighting.

Study on the experimental verification and regulatory mechanism of Rougui-Ganjiang herb-pair for the actions of thermogenesis in brown adipose tissue based on network pharmacology.

ETHNOPHARMACOLOGICAL RELEVANCE: Cinnamomum cassia Presl (Rougui) has character of xin、gan、wen, belongs to Jing of heart、lung、bladder, and has the effect of dispersing cold and relieving pain. It is widely used to resolve the exterior and dissipate cold in Treatise on Febrile Diseases (Shang Han Lun), such as Chaihu Guizhi Ganjiang Tang and Guizhi Renshen Tang. Both these two prescriptions contain Cinnamomum cassia Presl and Zingiber officinale Rosc (Ganjiang). Rougui-Ganjiang herb-pair (RGHP) can warm viscera and remove cold, which is widely used in Shang Han Lun. And in modern times, recent studies have showed that cinnamon and ginger also have the effect of thermogenesis and regulating the body temperature, respectively. AIM OF THE STUDY: To maintain the body thermal homeostasis and prevent cold invasion of main organs, in this study, we assessed the underlying physiological changes induced by RGHP in mice exposed to -20 °C and explored the mechanisms for the thermogenic actions of RGHP in brown adipose tissue (BAT) by network pharmacology and molecular docking. MATERIALS AND METHODS: Male Kunming (KM) mice were fed normal diet with orally administration of distilled water or ethanol RGHP extract (three doses: 375,750 and 1500 mg/kg) for 21 days, once per day and then exposed to -20 °C for 2 h. The core temperature, activity ability and the degree of frostbite in mice, morphological and ATP content of adipocytes were measured. In addition, the network pharmacology was employed to predict the targets of RGHP' s thermogenesis effect on BAT. Pathway analysis and biological process with key genes was carried out through KEGG and GO analysis, respectively. Furthermore, the core ingredients and targets obtained by network pharmacology were verified by molecular docking and Western blot assays. RESULTS: RGHP can significantly increase the core body temperature, reduce the degree of frostbite and enhance the activity ability of mice after cold exposure. Meanwhile, it can also improve the lipid morphology and decrease ATP production in BAT. A network pharmacology-based analysis identified 246 ingredients from RGHP (two herbs), which related to 222 target genes. There were 8 common genes between 222 compounds target genes and 62 thermogenesis associated target genes, which linked to 49 potential compounds. There are 24 ingredients which degree are greater than the average. Among them, we found that oleic acid, EIC, 6-gingerol, eugenol, isohomogenol and sitogluside could be detected in mice plasma. The cAMP-PPAR signaling pathway was enriched for thermogenesis after KEGG analysis with 8 genes. Molecular docking analysis and Western blot assay further confirmed that oleic acid, 6-gingerol, eugenol and isohomogenol were potential active ingredients for RGHP's heat production effect. And UCP1, PGC-1α, PPARα and PPARγ are key thermogenesis proteins. CONCLUSIONS: RGHP treatment can significantly maintain the rectal temperature of mice by enhancing the BAT heat production. RGHP exhibited the heat production effect, which might be mainly attributed to increasing thermogenesis through the cAMP-PPAR signaling pathway in cold exposure mice. Oleic acid, 6-gingerol, eugenol and isohomogenol might be considered the potential therapeutic ingredients which affect the key targets of thermogenesis effect.

[Applying Photochemical Indicators to Analyze Ozone Sensitivity in Handan].

Ozone pollution in Handan has become severe in recent years and in the summer of 2018, the average maximum daily 8-hour average ozone concentration in Handan was 175 µg·m-3 with a maximum of 257 µg·m-3. Ozone concentrations exceeded the National Air Quality Grade Ⅱ Standard in 59% of cases. In this study, the H2O2/HNO3 indicator was applied to analyze summertime ozone sensitivity in Handan using the WRF-CMAQ modeling system. The results showed that H2O2/HNO3 was more appropriate than other ozone indicators, both theoretically and based on simulation outputs. The good simulation effect of CMAQ on H2O2 and HNO3 was attributed to fine emission inventory and grid resolution. The H2O2/HNO3 simulation results showed that the relative importance of a VOCs-limited regime decreased month by month; a VOCs-NOx-mixed-limited regime was dominant in June; and a NOx-limited regime was more dominant in July and August than in June. The remarkable spatial difference in VOCs and NOx emission ratios among the counties of Handan led to differences in ozone sensitivity. The VOCs-limited regime was concentrated in counties where VOCs/NOx emission ratios were lower than 1.7. Southern counties had a NOx-limited regime, where VOCs/NOx emission ratios were higher than 6.9. Counties with VOCs/NOx emission ratios varying from 1.7 to 6.9 were more susceptible to both VOCs and NOx. According to these results, the transition range of HCHO/NO2, O3/HNO3, and O3/NOx ratios were adjusted to 0.35-0.6, 20-35, and 10-25 respectively. Adjusting the transition range of H2O2/(O3+NO2) was not effective, indicating that this indicator may not be applicable to Handan.