Electroencephalogram (EEG) is a non-invasive, high temporal-resolution technique for monitoring brain activity. However, affected by the volume conduction effect, EEG has a low spatial resolution and is difficult to locate brain neuronal activity precisely. The surface Laplacian (SL) technique obtains the Laplacian EEG (LEEG) by estimating the second-order spatial derivative of the scalp potential. LEEG can reflect the radial current activity under the scalp, with positive values indicating current flow from the brain to the scalp (“source”) and negative values indicating current flow from the scalp to the brain (“sink”). It attenuates signals from volume conduction, effectively improving the spatial resolution of EEG, and is expected to contribute to breakthroughs in neural engineering. This paper provides a systematic overview of the principles and development of SL technology. Currently, there are two implementation paths for SL technology: current source density algorithms (CSD) and concentric ring electrodes (CRE). CSD performs the Laplace transform of the EEG signals acquired by conventional disc electrodes to indirectly estimate the LEEG. It can be mainly classified into local methods, global methods, and realistic Laplacian methods. The global method is the most commonly used approach in CSD, which can achieve more accurate estimation compared with the local method, and it does not require additional imaging equipment compared with the realistic Laplacian method. CRE employs new concentric ring electrodes instead of the traditional disc electrodes, and measures the LEEG directly by differential acquisition of the multi-ring signals. Depending on the structure, it can be divided into bipolar CRE, quasi-bipolar CRE, tripolar CRE, and multi-pole CRE. The tripolar CRE is widely used due to its optimal detection performance. While ensuring the quality of signal acquisition, the complexity of its preamplifier is relatively acceptable. Here, this paper introduces the study of the SL technique in resting rhythms, visual-related potentials, movement-related potentials, and sensorimotor rhythms. These studies demonstrate that SL technology can improve signal quality and enhance signal characteristics, confirming its potential applications in neuroscientific research, disease diagnosis, visual pathway detection, and brain-computer interfaces. CSD is frequently utilized in applications such as neuroscientific research and disease detection, where high-precision estimation of LEEG is required. And CRE tends to be used in brain-computer interfaces, that have stringent requirements for real-time data processing. Finally, this paper summarizes the strengths and weaknesses of SL technology and envisages its future development. SL technology boasts advantages such as reference independence, high spatial resolution, high temporal resolution, enhanced source connectivity analysis, and noise suppression. However, it also has shortcomings that can be further improved. Theoretically, simulation experiments should be conducted to investigate the theoretical characteristics of SL technology. For CSD methods, the algorithm needs to be optimized to improve the precision of LEEG estimation, reduce dependence on the number of channels, and decrease computational complexity and time consumption. For CRE methods, the electrodes need to be designed with appropriate structures and sizes, and the low-noise, high common-mode rejection ratio preamplifier should be developed. We hope that this paper can promote the in-depth research and wide application of SL technology.

ObjectiveTo optimize Tusizi prescription for ovarian reserve function based on the uniform design method combined with in vitro experiments and explore the underlying mechanisms of this prescription. MethodsThe uniform design method was adopted to design a 5-factor 11-level experiment on the water extract of Tusizi prescription. The cell-counting kit-8 （CCK-8） assay was employed to measure the viability of human ovarian granulosa cells （KGN cells） treated with Tusizi prescription extracts 1-11， and multivariate regression analysis was performed to determine the optimal herb ratio in this prescription. The potential targets of active ingredients in the prescription were retrieved from traditional Chinese medicine systems pharmacology database and analysis platform （TCMSP） and encyclopedia of traditional Chinese medicine （ETCM）. The common targets shared by Tusizi prescription and diminished ovarian reserve （DOR） were selected and imported into search tool for the retrieval of interacting genes/proteins （STRING） to construct a protein-protein interaction （PPI） network and into gene function annotation database （DAVID） for gene ontology （GO） analysis. The CCK-8 assay was used to measure the viability of ovarian germline stem cells treated with hyperoside. The CCK-8 assay， 5-ethynyl-2'-deoxyuridine （EdU） staining， terminal-deoxynucleoitidyl transferase mediated nick-end labeling （TUNEL）， and enzyme-linked immunosorbent assay （ELISA） were employed to examine the proliferation， apoptosis， and estradiol （E₂） secretion of KGN cells treated with the water extract 11 of Tusizi prescription （Cuscutae Semen-Lycii Fructus-Dioscoreae Rhizoma-Poria-Nelumbinis Semen 4∶4∶2∶1∶1） and the optimal prescription screened by uniform design. On this basis， the optimal prescription composition for maximizing the effect on ovarian reserve function was determined and preliminary insights into the underlying mechanisms of this prescription were gained. ResultsA total of 147 common targets were obtained from 278 targets of Tusizi prescription and 1 721 targets of DOR. GO analysis revealed 194 biological processes， primarily involving cellular responses to exogenous compound stimuli， negative regulation of apoptotic process， and positive regulation of cell proliferation. It identified 84 cellular components， including cell membrane， mitochondria， and neuronal cell body， as well as 144 molecular functions such as enzyme binding， estrogen response element binding， and nuclear estrogen receptor binding. The multivariate regression analysis revealed that when Tusizi prescription was composed of Cuscutae Semen， Lycii Fructus， Dioscoreae Rhizoma， Poria， and Nelumbinis Semen in a ratio of 27∶30∶17∶12∶14， the water extract of Tusizi prescription had the best effect of enhancing the viability of KGN cells. CCK-8 results showed that compared with the normal group， the hyperoside group demonstrated increased viability of ovarian germline stem cells （P<0.01）. The CCK-8， EdU， and ELISA results showed that compared with the normal group， the optimal prescription screened by uniform design and the water extract 11 of Tusizi prescription increased the proliferation and reduced the apoptosis of KGN cells （P<0.05， P<0.01）. ELISA results showed that compared with the normal group， the water extract 11 of Tusizi prescription promoted the E₂ secretion of KGN cells （P<0.05）， while the optimal prescription screened by uniform design had no significant effect on the E₂ secretion. ConclusionBoth the water extract 11 of Tusizi prescription （Cuscutae Semen-Lycii Fructus-Dioscoreae Rhizoma-Poria-Nelumbinis Semen 4∶4∶2∶1∶1） and the optimal prescription screened by uniform design （Cuscutae Semen-Lycii Fructus-Dioscoreae Rhizoma-Poria-Nelumbinis Semen 27∶30∶17∶12∶14） can improve the ovarian reserve function， and the former has better effect. Tusizi prescription can modulate biological processes （such as cell proliferation and apoptosis） and molecular functions （such as enzyme binding and estrogen response element binding） through active components like hyperoside to promote the proliferation and E₂ secretion and inhibit the apoptosis of KGN cells， thereby protecting the ovarian reserve function.

ObjectiveTo optimize Tusizi prescription for ovarian reserve function based on the uniform design method combined with in vitro experiments and explore the underlying mechanisms of this prescription. MethodsThe uniform design method was adopted to design a 5-factor 11-level experiment on the water extract of Tusizi prescription. The cell-counting kit-8 （CCK-8） assay was employed to measure the viability of human ovarian granulosa cells （KGN cells） treated with Tusizi prescription extracts 1-11， and multivariate regression analysis was performed to determine the optimal herb ratio in this prescription. The potential targets of active ingredients in the prescription were retrieved from traditional Chinese medicine systems pharmacology database and analysis platform （TCMSP） and encyclopedia of traditional Chinese medicine （ETCM）. The common targets shared by Tusizi prescription and diminished ovarian reserve （DOR） were selected and imported into search tool for the retrieval of interacting genes/proteins （STRING） to construct a protein-protein interaction （PPI） network and into gene function annotation database （DAVID） for gene ontology （GO） analysis. The CCK-8 assay was used to measure the viability of ovarian germline stem cells treated with hyperoside. The CCK-8 assay， 5-ethynyl-2'-deoxyuridine （EdU） staining， terminal-deoxynucleoitidyl transferase mediated nick-end labeling （TUNEL）， and enzyme-linked immunosorbent assay （ELISA） were employed to examine the proliferation， apoptosis， and estradiol （E₂） secretion of KGN cells treated with the water extract 11 of Tusizi prescription （Cuscutae Semen-Lycii Fructus-Dioscoreae Rhizoma-Poria-Nelumbinis Semen 4∶4∶2∶1∶1） and the optimal prescription screened by uniform design. On this basis， the optimal prescription composition for maximizing the effect on ovarian reserve function was determined and preliminary insights into the underlying mechanisms of this prescription were gained. ResultsA total of 147 common targets were obtained from 278 targets of Tusizi prescription and 1 721 targets of DOR. GO analysis revealed 194 biological processes， primarily involving cellular responses to exogenous compound stimuli， negative regulation of apoptotic process， and positive regulation of cell proliferation. It identified 84 cellular components， including cell membrane， mitochondria， and neuronal cell body， as well as 144 molecular functions such as enzyme binding， estrogen response element binding， and nuclear estrogen receptor binding. The multivariate regression analysis revealed that when Tusizi prescription was composed of Cuscutae Semen， Lycii Fructus， Dioscoreae Rhizoma， Poria， and Nelumbinis Semen in a ratio of 27∶30∶17∶12∶14， the water extract of Tusizi prescription had the best effect of enhancing the viability of KGN cells. CCK-8 results showed that compared with the normal group， the hyperoside group demonstrated increased viability of ovarian germline stem cells （P<0.01）. The CCK-8， EdU， and ELISA results showed that compared with the normal group， the optimal prescription screened by uniform design and the water extract 11 of Tusizi prescription increased the proliferation and reduced the apoptosis of KGN cells （P<0.05， P<0.01）. ELISA results showed that compared with the normal group， the water extract 11 of Tusizi prescription promoted the E₂ secretion of KGN cells （P<0.05）， while the optimal prescription screened by uniform design had no significant effect on the E₂ secretion. ConclusionBoth the water extract 11 of Tusizi prescription （Cuscutae Semen-Lycii Fructus-Dioscoreae Rhizoma-Poria-Nelumbinis Semen 4∶4∶2∶1∶1） and the optimal prescription screened by uniform design （Cuscutae Semen-Lycii Fructus-Dioscoreae Rhizoma-Poria-Nelumbinis Semen 27∶30∶17∶12∶14） can improve the ovarian reserve function， and the former has better effect. Tusizi prescription can modulate biological processes （such as cell proliferation and apoptosis） and molecular functions （such as enzyme binding and estrogen response element binding） through active components like hyperoside to promote the proliferation and E₂ secretion and inhibit the apoptosis of KGN cells， thereby protecting the ovarian reserve function.

Objective : To investigate the antidepressant effects and the underlying mechanisms of tetrahydrocurcumin(THC) and its nanoparticle formulation(THCN). Methods : Forty-six male ICR mice were randomly divided into Con group, LPS group, THC group, THCN group and SER group. A mouse depression model was established by intraperitoneal administration of LPS. The anxiety and depression-like behaviors of mice were evaluated by open field test(OFT) and forced swimming test(FST). Myelin staining was applied to assess the extent of demyelination in the prefrontal cortex of the mice. The prefrontal cortex and hippocampus were further examined for the expression levels of glial fibrillary acidic protein(GFAP) and Toll-like receptor 4(TLR4) through quantitative immunofluorescence assays. Results : Compared with the Con group, the LPS group showed increased anxiety-like and depressive-like behaviors in both the long-term and short-term experiments(P<0.05); the degree of demyelination increased in the LPS group of the long-term experiment(P<0.01); the expression of GFAP was reduced in the LPS group of the short-term experiment(P<0.01), while the expression of TLR4 increased(P<0.05); the expression of TLR4 decreased in the THC group(P<0.01); the expression of GFAP in the prefrontal cortex of the THCN group was reduced(P<0.01), while the expression of TLR4 increased(P<0.05). Compared with the LPS group, the THC group showed reduced depressive-like behaviors in the long-term experiment(P<0.05), while the anxiety-like and depressive-like behaviors of the THCN group and the SER group were reduced(P<0.05), and the anxiety-like and depressive-like behaviors of the THC group and the THCN group were reduced in the short-term experiment(P<0.05); the degree of demyelination was reduced in the THC group, THCN group and SER group in the long-term experiment(P<0.05); the expression of GFAP increased in the THC group of the short-term experiment(P<0.05), while the expression of TLR4 was reduced(P<0.05), and the expression of GFAP increased in the THCN group(P<0.05). Compared with the THC group, the THCN group and the SER group showed reduced anxiety-like behaviors in the long-term experiment(P<0.05); the expression of GFAP in the prefrontal cortex of the THCN group was reduced in the short-term experiment(P<0.05), while the expression of TLR4 in the hippocampal DG area increased in the short-term experiment(P<0.01). Conclusion Tetrahydrocurcumin and its nanoparticle formulation both exert significant ameliorative effects on depression-like behaviors and demyelination in mice induced by lipopolysaccharide. The antidepressant mechanism of THC appears to be mediated through the down-regulation of TLR4 and the up-regulation of GFAP. The mechanism underlying the antidepressant action of THCN seems predominantly focused on the enhancement of GFAP expression.

Polycystic ovary syndrome （PCOS） is a common gynecological endocrine and reproductive disorder，with the main clinical manifestations including ovulation failure，insulin resistance，hyperandrogenism，and obesity. Its occurrence and development are closely related to cellular regulatory mechanisms such as apoptosis，autophagy，oxidative stress，and inflammatory response. Autophagy，as a clearance mechanism that maintains cellular homeostasis，plays a crucial role in maintaining the growth，development，and maturation of oocytes. Exploring the mechanism of autophagy during the occurrence and development of diseases can help develop treatment methods for PCOS by regulating autophagy. Studies have shown that autophagy plays an important role in the pathogenesis of PCOS，and it can affect the occurrence and development of PCOS through multiple pathways，levels，and targets. Traditional Chinese medicine （TCM） regulates autophagy in ovarian granulosa cells or endometrium of patients with PCOS by targeting the expression of autophagy signaling pathways，regulatory factors，and non-coding single-stranded RNA molecules，thereby alleviating inflammation，regulating metabolism disorders，and balancing hormone levels in PCOS. Accordingly，TCM can ameliorate pathological conditions such as insulin resistance，hyperandrogenism，and ovulation failure in PCOS. This article summarizes the TCM formulas and extracts for the treatment of PCOS，as well as the main autophagy pathways and regulatory factors involved，aiming to provide reference and suggestions for the future treatment of PCOS with TCM by regulating autophagy.

Objective: To evaluate the comprehensive intervention effect of lunch for primary and secondary school students in Minhang District, so as to provide a theoretical and practical basis for lunch intervention in school. Methods: From October to December 2023, a convenience sampling method was used to select 1 937 students from one primary and secondary school in Minhang District.A comprehensive intervention measure focusing on "reducing oil and salt" for lunch recipe optimization and nutrition education was carried out, and a questionnaire survey was conducted to evaluate the intervention effect three months later. Chi square test and Wilcoxon rank test were used to compare the data before and after the intervention. Results: After intervention, the use of cooking oil and salt, the supply of protein and fat in primary and secondary school lunches were reduced, and had no obvious impact on energy and other major nutrients. After intervention, compared to before intervention, the proportion of primary school students who felt that lunch was greasy decreased (8.9%, 6.2%, χ 2=4.35), and the proportion of primary and secondary school students who felt that lunch were delicious decreased significantly (33.2%, 23.2%; 63.9%, 53.5%, χ 2=26.39, 17.52) ( P < 0.05 ). Secondary school students also felt reduced variety of food ingredients (46.9%, 38.3%, χ 2=16.05, P <0.05). In addition, after intervention, the total surplus rate of primary school students meals decreased (7.4%, 4.4%, χ 2=5.73), mainly reflected in the decrease of the surplus rate of staple foods (7.1%, 2.4%, χ 2=17.39), while the surplus rate of vegetable dishes increased ( 16.0 %, 21.2%, χ 2=6.01) ( P <0.05). Although there was no significant change in the total surplus rate of meals for secondary school students, the surplus rate of staple foods decreased (12.9%, 5.4%, χ 2=33.52), while the surplus rates of meat and vegetable dishes increased (11.2%, 26.9%; 17.5%, 33.2%, χ 2=74.26, 61.88) ( P <0.05). After intervention, there was no statistically significant difference in the overweight and obesity rates of primary school students ( χ 2=0.11,0.43) and secondary school students ( χ 2=0.01,0.00) compared to before intervention( P >0.05). After intervention, the lung capacity of primary school students [1 564 (1 269,1 890) mL] and sitting forward flexion [11.3 (7.6, 15.2) cm] increased compared to before intervention [1 522 (1 259, 1 819 ) mL, 10.5 (6.3, 13.5) cm] ( Z =2.20, 4.68, P <0.01), but there was no statistically significant difference in lung capacity and sitting forward flexion of secondary school students before and after intervention ( Z =-0.46, -0.08, P >0.05). Conclusion The comprehensive intervention of school lunch has promoted a significant decrease in the use of oil and salt in lunch and improved the quality of recipes, and has a positive impact on the situation of leftover lunch and the health of students to a certain extent.

Objective To evaluate the removal efficiency of chromatography process for impurity proteins[IFN-related proteins and host cell proteins (HCPs)]in the purification process of human interferon α2b (h IFNα2b) by liquid chromatogra-phyhigh resolution mass spectrometry (LC-HRMS),in order to provide experimental basis for improving the production process of h IFNα2b.Methods The whole protein levels of IFN-related proteins (including deamidated IFN,oxidized IFN and acetylated IFN) and HCPs during the chromatography process of h IFNα2b were analyzed by LC-HRMS,and the h IFNα2b post-translational modification sites and HCPs were detected on the polypeptide levels.Results HCPs could be removed by hydrophobic interaction chromatography (HIC) M column,HCPs,deamidated IFN and acetylated IFN could be removed by anion exchange chromatography (AEC),and oxidized IFN could be removed by HIC (B column).The major acetylation sites (K34,K121,K131 and K134),major oxidation sites (M16,M21,M59 and M148),as well as Q5 and Q21 of major deamidation sites (N45,N156,Q5,Q21,Q46 and Q124) of h IFNα2b were located on the surface of the protein,which were susceptible to environmental conditions and subjected to acetylation and oxidation.Conclusion In the purification process of h IFNα2b,chromatography purification can effectively remove IFN-related proteins and HCPs,which also indicated that LC-HRMS technology can be used for the research of IFN purification process.

ObjectiveBased on the TCM theory of "Yang transforms materials to Qi while Yin constitutes material form"， this paper explored the effects of Zuogui Wan and Yougui Wan on the molecular mechanism of mitochondrial biogenesis during the adipogenic differentiation process of rat bone marrow mesenchymal stem cells （BMSCs） by mediating peroxisome proliferator-activated receptor γ coactivator-1α （PGC-1α） and peroxisome proliferators-activated receptor γ （PPARγ）， providing theoretical support for the prevention and treatment of postmenopausal osteoporosis （PMOP） using Zuogui Wan and Yougui Wan. MethodsBMSCs were divided into a blank group， Zuogui Wan （ZGW） group， Yougui Wan （YGW） group， and Progynova group. Cell identification was performed using flow cytometry. The growth curves of BMSCs were plotted using the methylthiazolyldiphenyl-tetrazolium bromide （MTT） method， and the effects of Zuogui Wan and Yougui Wan on the proliferation of BMSCs were detected. The Oil red O staining method was used to detect lipid droplet formation. The Western blot method was used to detect the expression of adipogenesis-related factors PPARγ， CCAAT/enharcer-binding protein （C/EBP）α， C/EBPβ， lipoprotein lipase （LPL） protein， brown adipose tissue-related （BAT） proteins PGC-1α， uncoupcing protein 1 （UCP1）， PR domdin-containing protein 16 （PRDM16）， mitochondrial biogenesis-related PGC-1α， nuclear respiratory factor 1 （Nrf1）， nuclear factor E₂-related factor 2 （Nrf2）， and mitochondrial transcription factor A （TFAM）. The expression of adipogenesis-related factors PPARγ， C/EBPα， C/EBPβ， LPL genes， and the copy number of cytochrome B （CytoB mtDNA） gene was detected using real-time polymerase chain reaction （Real-time PCR）. Mitochondrial ultrastructure was detected using transmission electron microscopy. ResultsCompared with that in the blank group， the proliferation ability of BMSCs in each treatment group increased continuously as the intervention progressed， and lipid droplets significantly decreased after the drug intervention. The mRNA and protein expression levels of adipogenesis-related factors PPARγ， C/EBPα， C/EBPβ， and LPL were significantly downregulated （P<0.01）， while those of the BAT-related factors PGC-1α， UCP1， PRDM16 were significantly upregulated （P<0.01）. The number of mitochondria increased， accompanied by reduced swelling. The double membrane and cristae structure were clear， and the internal cristae rupture was reduced. The copy number of CytoB mtDNA in each treatment group was significantly increased （P<0.01）. The protein expression levels of mitochondrial biogenesis-related PGC-1α， Nrf1， Nrf2， and TFAM in each treatment group were significantly increased （P<0.01）. ConclusionBoth Zuogui Wan and Yougui Wan can prevent and treat PMOP by intervening in mitochondrial biogenesis in BMSCs through PGC-1α/PPARγ.

ObjectiveTo explore the effectiveness of health information dissemination and its influencing factors using the "Shanghai CDC" WeChat public account as a case study, providing references for public health institutions to optimize the use of official new media platforms for effective publicity. MethodsA total of 1 030 headline articles published on the "Shanghai CDC" WeChat public account between 2016 and 2019 were analyzed using content analysis and non-parametric tests to examine the impact of factors such as titles and content categories. ResultsFrom 2016 to 2019, the number of WeChat public account followers increased by 280 000, with the articles accumulating over 8.8 million views. The median (P₂₅, P₇₅) open rate of articles was 5.90% (3.69%, 10.31%), and the median (P₂₅, P₇₅) sharing and forwarding rate was 6.60% (4.25%, 9.17%). Factors such as the use of first- and second-person pronouns, degree adverbs, negative adverbs, explicit viewpoints, and title length all significantly affected the open rate of articles, with OR (95%CI) values of 0.175 (0.041‒0.756), 32.606 (2.350‒452.432), 4.079 (1.093‒15.230), 0.106 (0.028‒0.409), and 1.184 (1.063‒1.319),respectively (all P<0.05). In terms of content, statistical significant differences in dissemination effectiveness were observed across article categories and themes (P<0.05). In terms of article categories, articles related to news hotspots and service information had higher open rates of 9.58% and 14.00%, respectively. These two types of articles also obtained higher sharing and forwarding rates of 7.65% and 9.16%, respectively. In terms of article topics, compared with healthy life and health products, among the top four topics in terms of publication volume, the open rates of articles about infectious diseases and disease-causing biology and immunization programs were higher, accounting for 7.88% and 6.88%, respectively, with no significant difference in sharing and forwarding rates. ConclusionThe "Shanghai CDC" WeChat public account demonstrated good dissemination effectiveness. Enhancing article titles by increasing informational content and degree adverbs (e.g., "highly," "most," and "extremely") and negative adverbs (e.g., "no") can improve dissemination reach. Public health WeChat accounts should incorporate news hotspots or service information in their articles. While maintaining their strengths in disseminating knowledge on infectious diseases and immunization programs, they should also enhance public education in other professional fields within their scope of responsibility to improve the overall dissemination impact of health information.

Background Polycyclic aromatic hydrocarbons (PAHs) are widely known atmospheric pollutants, which can cause serious harm to human body and ecological environment. Objective To analyze the concentrations and sources of PAHs in atmospheric PM_2.5 in Zhifu District and Longkou City during the heating period in Yantai. Methods Two monitoring sites in Zhifu District and Longkou City of Yantai were selected, and PM_2.5 sample collection was carried out from April 2023 to March 2024. Gas chromatography-mass spectrometry was applied to analyze the concentrations of PAHs in atmospheric PM_2.5 during the heating period (from November 2023 to March 2024) and the non-heating period (from April to October 2023). The concentrations of PAHs in the two periods were compared and the sources of PAHs during the heating period were analyzed by characteristic ratio method. Results During the heating period, the total concentration ranges of PAHs in atmospheric PM_2.5 at the monitoring sites in Zhifu District and Longkou City of Yantai were (1.59-23.70) ng·m⁻³ and (2.08-149.72) ng·m⁻³ respectively, and the medians (M) and the 25th and 75th percentiles (P₂₅, P₇₅) were 4.99 (2.61, 8.09) ng·m⁻³ and 15.46 (8.15, 29.05) ng·m⁻³ respectively. The PAHs concentrations in Longkou City were significantly higher than those in Zhifu District in all months (P<0.05). The highest median total concentrations of PAHs in both sites were reported in January (8.14 ng·m⁻³ and 81.56 ng·m⁻³ respectively). In the non-heating period, the M (P₂₅, P₇₅) of the total PAHs concentrations at the two sites were 1.59 (1.59, 2.78) ng·m⁻³ and 4.11 (2.94, 7.97) ng·m⁻³ respectively, much lower than those in the heating period (P<0.01). The order of composition of PAHs by ring number in PM_2.5 at both sites was 4-ring> 5-ring> 6-ring, with the 4-ring contributing the largest proportion (65.33% and 46.39% respectively). Fluoranthene had the highest concentration among PAHs at both sites, with concentrations M (P₂₅, P₇₅) of 1.29 (0.51, 1.78) ng·m⁻³ and 2.32 (1.30, 3.82) ng·m⁻³ respectively. The characteristic ratios of fluoranthene/(fluoranthene + pyrene), fluoranthene/pyrene, benzo[a]anthracene/(benzo[a]anthracene + chrysene), pyrene/benzo[a]pyrene, benzo[a]pyrene/(benzo[a]pyrene + chrysene), benzo[a]pyrene/benzo[g,h,i]pyrene, and indeno[1,2,3-c,d]pyrene/(indeno[1,2,3-c,d]pyrene + benzo[g,h,i]pyrene) in Zhifu District were 0.62, 1.65, 0.41, 4.48, 0.50, 0.93 and 0.47 respectively, and those in Longkou were 0.57, 1.35, 0.40, 2.89, 0.29, 0.79 and 0.47 respectively. The results showed that PAHs pollutants were generated by combination of coal combustion, vehicle exhaust emissions and gasoline combustion. Conclusion During the heating period in Yantai area, the total concentration of PAHs in atmospheric PM_2.5 is significantly higher than that in the non-heating period. Among them, during the heating period, the pollution level in Longkou City is significantly higher than that in Zhifu District. The local PAHs may be sourced from mixed pollution, and the main sources include gasoline, and coal combustion and vehicle exhaust emissions.