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Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (1): 0-.   Abstract （541）   HTML    PDF（pc） （1861KB）（5501）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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Characteristics of Temporal and Spatial Distribution of Atmospheric PM10 and PM2.5 in Tibet Region WANG Caihong, SONG Guofu, NIMAZHUOMA, WANG Yongpeng, ZHAO Kuang Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (2): 195-205.   DOI: 10.13209/j.0479-8023.2024.116 Abstract （3395）   HTML    PDF（pc） （1593KB）（5194）       Knowledge map    Save Based on the ambient air quality monitoring data of 7 cities in Tibet from 2017 to 2023, the spatial and temporal distribution characteristics of PM10 and PM2.5 in ambient air in Tibet were analyzed by correlation analysis and GIS Kriging interpolation. The results showed that in Tibet region, the days with PM10 and PM2.5 as the primary pollutants were characterized by good ambient air quality, mainly concentrated in January–March and October–December. The variation trend of PM10 and PM2.5 concentration was consistent. The average annual concentration in the whole region reached the first-level standard and showed a downward trend, and the seasonal average concentration showed the characteristics of winter>spring>autumn>summer. The average monthly concentration began to decrease from May, reaching the lowest in August and the highest in December. The hourly concentration showed bimodal characteristics, and the peak appeared from 09:00 to 12:00 in the morning and from 21:00 to 01:00 in the next day. The concentrations of PM10 and PM2.5 in Nyingchi City in southeastern Tibet were significantly lower than those in other cities, while the concentrations of PM10 and PM2.5 in Nagqu City in northern Tibet were significantly higher than those in other cities. According to the analysis of Sugimoto model, in the exceedance days with particulate matter as the primary pollutant, dust weather had a particularly significant impact on the concentration of PM10 in the atmospheric environment of Tibet, the average content of dust components in PM10 was 87.9%.  Related Articles | Metrics | Comments（0）

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Exploring the Effects of Malt on Beer Flavor and Yeast Metabolic Pathways by Metabolomic Technology LI Jingting, SUN Zhen, TANG Wenzhu Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (4): 617-628.   DOI: 10.13209/j.0479-8023.2025.044 Abstract （1087）   HTML    PDF（pc） （4361KB）（5108）       Knowledge map    Save In order to explore the effects of different malts on the flavor of beer after fermentation, the differences between 5 barley malts and 5 wheat malts on beer composition were analyzed by using metabolomics methods. The effects of different malts on the metabolic pathway of Saccharomyces cerevisiae during beer fermentation were explained at the metabolic level. After liquid chromatography-mass spectrometry (LC-MS) detection, principal component analysis (PCA) and orthogonal partial least squares discriminant analysis were performed to screen out the key metabolites that had the greatest impact on beer flavor. After linking the key metabolites to the flavor of beer, pathway enrichment was carried out. The results determined that barley malt mainly affects Purine metabolism, Pyrimidine metabolism, Arginine and proline metabolism, Alanine, aspartic acid and glutamate metabolism, Arginine biosynthesis, β-Alanine metabolism, Nicotinate and nicotinamide metabolism, Galactose metabolism and other pathways. Wheat malt mainly affects Purine metabolism, Pyrimidine metabolism, Arginine and proline metabolism, and Glutathione metabolism. These metabolic pathways have a key impact on the flavor of beer, which provides some theoretical guidance for the regulation of flavor substances in beer. Related Articles | Metrics | Comments（0）

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Acta Scientiarum Naturalium Universitatis Pekinensis    2024, 60 (6): 0-.   Abstract （539）   HTML    PDF（pc） （2067KB）（4964）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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A Multimodal Cross-Attention Model for Alzheimer’s Disease Diagnosis LI Zhou, LIU Yongbin, OUYANG Chunping, ZHANG Jiangtao, PAN Xue, JIANG Lu, ZHONG Jin Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (4): 629-638.   DOI: 10.13209/j.0479-8023.2024.121 Abstract （2250）   HTML    PDF（pc） （1233KB）（4904）       Knowledge map    Save In order to achieve accurate computer-aided diagnosis of Alzheimer’s disease (AD)and mild cognitive impairment (MCI) patients, this paper proposes a multimodal Alzheimer’s multi-class diagnostic framework (MAMDF) that uses an asymmetric cross-attention mechanism for multimodal fusion to better reveal the relationship between clinical data and medical imaging data. Moreover, to address the two MCI subtypes that are rarely mentioned in previous computer-aided diagnosis work, we combined frequency-domain transformers and Transformers to propose a novel deep feature extraction module for feature fusion. This method captures the internal connections of fused features and obtains richer multimodal joint representations, thus improving the diagnostic performance of the model on the two MCI subtypes. Experimental results on the ADNI dataset show that the proposed model achieves higher accuracy and F1 scores, compared with similar works. Thus the model can more effectively handle multimodal data fusion and mine the deep feature relationships between different modal medical data, thereby better integrating and analyzing the multimodal information of AD patients.  Related Articles | Metrics | Comments（0）

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Acta Scientiarum Naturalium Universitatis Pekinensis    2024, 60 (5): 971-972.   Abstract （592）   HTML    PDF（pc） （250KB）（4883）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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Twitter Bot Detection Method Based on Social Temporal Knowledge Graph JIANG Zhishu, CHEN Wei, ZHANG Weijie, ZHANG Shiqi, CHEN Jiruo, WAN Huaiyu Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (4): 639-649.   DOI: 10.13209/j.0479-8023.2024.120 Abstract （1078）   HTML    PDF（pc） （2643KB）（4804）       Knowledge map    Save Existing Twitter bot detection methods often overlook the structural and temporal information of users’ dynamic social history, as well as the noise accumulation resulting from feature fusion. In order to address these limitations, this paper constructs STKG (social temporal knowledge graph) and proposes a Twitter bot detection method STKGBot (STKG for Twitter bot detection). In the STKG, STKGBot uses RE-GAT (heterogeneity-enhanced graph attention network) to learn the static social relationship feature, TE-GCN (temporal-enhanced graph convolutional network) to learn the dynamic social history feature, and a bilinear model for the feature fusion. In addition, STKGBot employs contrastive learning to alleviate the noise aggravation in the process of feature fusion. Experimental results on two public datasets demonstrate that STKGBot outperforms state-of-the-art models. Related Articles | Metrics | Comments（0）

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Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (2): 0-.   Abstract （888）   HTML    PDF（pc） （1923KB）（4682）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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Focal Mechanisms of Small Earthquakes and Tectonic Stress Field Study in Zemuhe-Xiaojiang Fault WANG Longtan, PIAO Jian, ZHOU Shiyong Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (4): 659-667.   DOI: 10.13209/j.0479-8023.2024.093 Abstract （773）   HTML    PDF（pc） （5112KB）（4653）       Knowledge map    Save This study employs a broadband seismometers network around the Zemuhe-Anninghe Fault zone in Yunnan to detect and locate earthquakes from 2015 to 2019, yielding 11091 event locations. Seismic activity is concentrated at the intersection of the Zemuhe Fault and the Xiaojiang Fault, with the locations revealing the spatial relationship between these two fault zones. The distribution of earthquakes shows significant spatial clustering and indicates numerous secondary structures beyond the main faults. Based on these high-precision microearthquake locations, 1462 focal mechanism solutions were calculated, predominantly showing strike-slip movements. At the intersection of the Zemuhe and Xiaojiang faults, a concentration of normal fault type earthquakes aligns with the characteristics of the regional extensional basin. Average focal mechanism solutions and structural stress field inversion results indicate some rotation of stress fields across different regions; from north to south, the principal stress axis rotates clockwise by approximately 15°. The southern segment of the Zemuhe Fault and the northern segment of the Xiaojiang Fault have R values of 0.28 and 0.10, respectively, reflecting characteristics of both strike-slip and extension. The complexity of the stress fields within the study area reflects the presence of multiple scales of tectonic stress loading patterns.  Related Articles | Metrics | Comments（0）

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Acta Scientiarum Naturalium Universitatis Pekinensis    2024, 60 (5): 0-.   Abstract （908）   HTML    PDF（pc） （2139KB）（4594）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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Causes of PM2.5 Pollution in the Core Area of Ili River Valley in Winter LI Shuai, HONG Wen, GUO Liyao, BAI Wenyu, GENG Chunmei, ZHAO Xueyan, YANG Wen Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (2): 206-216.   DOI: 10.13209/j.0479-8023.2024.123 Abstract （2218）   HTML    PDF（pc） （5186KB）（4590）       Knowledge map    Save To investigate the causes and sources of atmospheric fine particulate matter (PM2.5) pollution in the core area of the Ili River Valley in winter, environmental air particles were collected at 6 sampling sites in the core area, including Yining City and its surrounding counties from December 27, 2021 to January 12, 2022. A total of 58 components, including inorganic elements, water-soluble ions, and carbon components, were analyzed, and positive matrix factorization (PMF) was employed for source apportionment. The results showed that the mean concentration of PM2.5 during the sampling period was 83±35 μg/m3. Three monitoring sites in Yining City showed the highest pollution levels, followed by Huocheng County. The concentration of SO42− in PM2.5 was the highest (14.1 μg/m3), followed by NO3− (10.5 μg/m3), NH4+ (8.2 μg/m3), and Cl− (1.6 μg/m3), indicating that coal combustion contributed significantly to pollution in winter. The concentrations of SO42− (16.5 μg/m3), NO3− (11.8 μg/m3), and NH4+ (9.5 μg/m3) reported by Yining City's Ecological Environment Bureau were significantly higher than those at other sites. Sulfur oxidation rate (SOR) and nitrogen oxidation rate (NOR) during air pollution were significantly higher than those in clean days, indicating a strong secondary transformation process. The source apportionment results showed that secondary particles had the highest contribution rate (40%), followed by biomass burning (24%), dust sources (14%), coal combustion (11%), industrial sources (6%), and vehicle sources (4%). Compared to clean days, the contribution rate of secondary particles significantly increased during air pollution, with a 27% increase in the contribution rate, mainly due to the accumulation of precursor concentrations in polluted weather conditions and the favorable conditions for the formation of secondary particles in high humidity. The contribution rate of secondary particles to PM2.5 in the core area of the Ili River Valley was slightly higher than that in other Chinese cities. The contribution rate of biomass burning sources was higher. Therefore, local control measures are needed to strengthen regulation of local coal combustion, vehicle sources, and biomass burning sources. Related Articles | Metrics | Comments（0）

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Dynamics Study on Spring Separation Device of the Asymmetric Satellite-Rocket with Large Inclination LIU Jiajia, LI Jiaquan, WANG Xuefeng, GAO Lijun, GONG Linhui, LIU Caishan Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (3): 411-419.   DOI: 10.13209/j.0479-8023.2024.037 Abstract （2163）   HTML    PDF（pc） （2517KB）（4529）       Knowledge map    Save In order to better control the motion state of the satellite and achieve precise orbit insertion, it is necessary to assess the sensitivity of the satellite to the physical parameters of the system during the satellite rocket separation process. This paper proposes a simplified two-dimensional dynamic model for the complex layout scheme of separation of large angle asymmetric star rocket joint surfaces, which simplifies the complex three-dimensional dynamic problem into a planar dynamic problem, reduces the system’s degrees of freedom, and greatly simplifies the computational difficulty of the model. The simulation results indicate that by appropriately configuring the preload of built-in springs and interface friction properties, the initial attitude of satellite orbit insertion can be effectively controlled. The research results can provide guidance for the parameter design of satellite-rocket separation devices. Related Articles | Metrics | Comments（0）

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Sentiment Analysis of Chinese Ancient Poetry by Fusing Explicit Knowledge and Implicit Knowledge ZHAO Yulan, WAN Guangwen, LIU Zhongbao Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (3): 420-430.   DOI: 10.13209/j.0479-8023.2025.002 Abstract （3951）   HTML    PDF（pc） （746KB）（4522）       Knowledge map    Save By fully utilizing the features of poetry text and related knowledge, this paper proposes a model SACAP for sentiment analysis of Chinese ancient poems integrating explicit knowledge and implicit knowledge. On the one hand, the model extracts deep semantic features from poetry text, and on the other hand, on the basis of constructing a knowledge base of Chinese ancient poetry, it designs a multidimensional attention mechanism to extract features from Chinese ancient poetry knowledge. The sentiment of Chinese ancient poetry can be determined by taking both features into consideration. The experimental results show that the proposed model performs better than existing models and the explicit knowledge plays much more important role, compared with implicit knowledge. Related Articles | Metrics | Comments（0）

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Construction of Emission Inventory and Temporal-Spatial Distribution of Soil Fugitive Dust in Typical Oasis Cities BAI Wenyu, LI Xiaofang, ZHANG Hongbin, WANG Jing, ZHAO Xueyan, LAI Xiaoshan, HONG Wen, JIANG Yan Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (2): 217-226.   DOI: 10.13209/j.0479-8023.2024.115 Abstract （1884）   HTML    PDF（pc） （2418KB）（4496）       Knowledge map    Save To evaluate the contribution of soil wind erosion to the particulate matter emissions of oasis cities, based on collected activity levels and emission factors related to soil fugitive dust, a 3 km×3 km-gridded emission inventory of PM2.5 and PM10 from soil fugitive dust in Xinjiang typical oasis cities (Altay City, Yizhou District of Hami City, and Kashgar City) in 2021 was developed in combination with Emission Factors and GIS technology. The results showed that the total emissions of PM10 from soil fugitive dust in Altay City, Kashgar City, and Yizhou District of Hami City were estimated to be 40983.79, 6541.97, and 1974362.24 t, respectively. The total emissions of PM2.5 were estimated to be 7069.69, 1090.49, and 326187.68 t, respectively. The particulate matter emission of Yizhou District of Hami City was the highest among the study areas, and the emission of PM10 is 302 times and 48 times higher than that of Kashgar and Altay. Due to factors such as soil type, location in the sand source area, and high wind speed, the emission intensity of particulate matter from soil wind erosion in Yizhou District of Hami City was also significantly higher than that of the other two cities. The temporal distribution characteristics in Yizhou District of Hami City showed a unimodal pattern, with the highest occurring in May. Kashgar City and Altay City both showed a bimodal pattern, with Kashgar City’s peaks occurring in June and August, and Altay City’s peaks occurring in May and July.  Related Articles | Metrics | Comments（0）

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Characteristics and Source Apportionment of Atmospheric VOCs in Urumqi and Karamay Cities JI Yuan, LIU Yanhui, LIU Xi, SUN Lin, SONG Yuqiao, BAI Shanshan, ZHAO Xinting, GENG Chunmei, YANG Wen Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (2): 227-239.   DOI: 10.13209/j.0479-8023.2024.119 Abstract （1621）   HTML    PDF（pc） （3629KB）（4477）       Knowledge map    Save Continuous measurements of 116 volatile organic compounds (VOCs) species by online gas chromato-graphy-mass spectrometry (GC-MS) from autumn 2023 to summer 2024 in Urumqi and Karamay were used to investigates the pollution characteristics of VOCs, the potential contribution to secondary pollutants, and their sources. The results showed that the average VOC concentration in Urumqi ((31.08±20.7)×10−9) was higher than in Karamay ((23.08±20.9)×10−9). Both cities showed a seasonal variation trend with lower VOCs concentrations in spring and summer and higher concentrations in autumn and winter. In Urumqi, alkanes (38.7%) and oxygenated volatile organic compounds OVOCs (16.7%) were the primary components of VOCs, whereas in Karamay, the proportion of alkanes reached as high as 47.2%, followed by alkenes (13.7%). The ozone formation potential of VOCs in Urumqi and Karamay in summer was 139.2 μg/m3 and 46.7 μg/m3, respectively, mainly contributed by OVOCs (38.2% and 41.8%). In winter, secondary organic aerosol formation potential were 0.59 μg/m3 and 0.41 μg/m3, respectively, mainly contributed by aromatics (89.8% and 84.8%). OH reactivity in Urumqi (5.0 s−1) was higher than that in Karamay (2.6 s−1). Alkenes were found to be the major contributor to OH reactivity. Positive matrix factorization (PMF) source analysis for the two cities revealed great similarity, with the common factors including combustion, traffic exhaust, solvent evaporation, industrial emissions, and regional background. Combustion and traffic exhaust contributed the most to ambient VOCs concentrations in Urumqi and Karamay at 23.8% and 23.5%, respectively, which was high compared with other cities in China. Related Articles | Metrics | Comments（0）

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End-to-End Spanning Tibetan Semantic Role Labeling Based on Graph Parsing BAN Mabao, LUO Peng, Thupten Tsering, Nyima Tashi, CAI Rangjia, YU Yongbin Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (3): 440-450.   DOI: 10.13209/j.0479-8023.2025.038 Abstract （1849）   HTML    PDF（pc） （1808KB）（4348）       Knowledge map    Save Semantic role labeling, as an essential pathway to semantic understanding, has a wide range of applications in machine translation, information extraction, and question and answer systems. This paper proposes a graph parsing-based end-to-end spanning semantic role labeling method for Tibetan, based on existing Tibetan semantic labeling systems and methods, by referring to the more mature semantic role labeling methods in English and Chinese. The method converts span-based semantic role labeling in Tibetan into a word-based graph parsing task, and the process is divided into two phases: semantic role labeling to graph conversion and graph to semantic role labeling recovery. In the first stage, a Tibetan pre-training language model (TiUniLM) is used for dynamic word embedding, and predicates are automatically specified by introducing the predicate indicator P. Then, temporal features are further modeled by designing a "gating" mechanism long short-term memory network (GM-LSTM). The second stage uses Viterbi constraint decoding to correct the illegitimate graphs. Experiments on TSRLD-Span show that the proposed method can achieve the best F1 value of 89.69% on the test set, which is a significant improvement in performance compared with the baseline model, indicating that the method is effective. Related Articles | Metrics | Comments（0）

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Paleogeomorphology and Tectonic Activity Processes in Yamal-Gyda Region of the Northern West Siberian Basin MO Wuling, JI Zhifeng, JIANG Ren, ZHANG Yiqiong Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (4): 668-686.   DOI: 10.13209/j.0479-8023.2025.058 Abstract （588）   HTML    PDF（pc） （79162KB）（4327）       Knowledge map    Save The northern West Siberian Basin developed tectonic activity during the Triassic period with the development of rift systems and throughout the Mesozoic-Cenozoic era with the formation of numerous local tectonic uplifts. In view of the fact that there is no unified and clear understanding on the formation mechanisms of the geological features, this paper presents a detailed analysis of deep linear structures of the pre-Mesozoic basement, the tectonic evolution of sedimentary cover, the paleogeomorphology, and tectonic activity processes of Yamal-Gyda region. The results reveal that: 1) Deep linear structures can be categorized into four groups of directions, NW, NE, nearly E-W and nearly N-S. The NW and NE linear structures are the structural responses of the folds, thrusts, reverse faults and strike-slip faults of the pre-Mesozoic basement linked to the Ural fold system. The nearly N-S lineaments are clearly identifiable normal faults that mark the western boundary of the Triassic rifting graben. 2) Normal faults (stretching) and anticlines (compression) exhibit identical tectonic orientations. These structures developed sequentially, first through dextral strike-slip faulting in the NW direction and subsequently through sinistral strike-slip faulting in the NE direction. Anticlines formed under the influence of these dual strike-slip movements, with most normal faults developing during the dominant right-lateral phase. 3) The initiation of most uplifts and faults occurred during the Jurassic period, followed by multiple episodes of reactivation of deep linear structures. These tectonic activities are closely linked to Late Cimmerian folding, the collision between the Eurasian Plate and the Indian Plate, as well as widespread regional extensional and rifting processes across the northern part of the Eurasian continent. 4) The majority of uplifts are likely tied to differential vertical movements generated during the activation of deep linear structures. The NE and NNE-trending uplifts and lineaments correlate with folds, reverse faults, and thrust faults associated with the Urals-Novaya Zemlya fold belt, while NW-trending uplifts and lineaments correspond to the dextral strike-slip faults across the Eurasia continent. Related Articles | Metrics | Comments（0）

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A Large Range and Low Noise Vector Magnetometer for Magnetic Target Recognition YU Xiangqian, HE Donghua, SHI Weihong, XIAO Chijie, LIU Si, ZONG Qiugang, CHEN Hongfei, WANG Linghua, ZOU Hong, WANG Yongfu Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (3): 451-455.   DOI: 10.13209/j.0479-8023.2025.039 Abstract （1633）   HTML    PDF（pc） （2867KB）（4326）       Knowledge map    Save According to the need for large range, low noise vector magnetic field detection systems in magnetic source target recognition, a vector magnetometer based on magnetoresistive sensor HMC1021Z is proposed. Through experimental testing, the magnetic field detection range of the vector magnetometer can be as high as ± 6×105 nT. At the same time, it has a high linearity, and the nonlinear error is ≤5.6‱. Root mean square (RMS) noise is 1.2611 nT and power spectral density (PSD) noise is 0.8 nT/√Hz@1 Hz. −3 dB bandwidth is DC to 8 Hz. All these characteristics make the proposed vector magnetometer meet the requirements of magnetic field detection with large range and low noise in magnetic target recognition applications. Related Articles | Metrics | Comments（0）

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Acta Scientiarum Naturalium Universitatis Pekinensis    2024, 60 (4): 0-.   Abstract （435）   HTML    PDF（pc） （2094KB）（4265）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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Characteristics of Water-Soluble Inorganic Ions in PM2.5 of Kunming Based on On-line Monitoring ZU Kexin, GONG Yuanjun, DONG Huabin, SONG Mengdi, LU Keding Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (2): 265-276.   DOI: 10.13209/j.0479-8023.2024.114 Abstract （2299）   HTML    PDF（pc） （3363KB）（4199）       Knowledge map    Save To explore the characteristics and sources of water-soluble inorganic ions in PM2.5 of Kunming, simultaneously on-line measurements of major water-soluble inorganic ions and gaseous pollutants were performed from April 15 to May 20, 2021 in Xishan district, Kunming city using a Gas-aerosol Collector and Ion Chromatograph (GAC-IC). The results showed that the average mass concentration of PM2.5 was 25.0±15.0 μg/m3, indicating that the atmosphere of Kunming was at a relatively clean level, and the average mass concentration of water-soluble ions was 8.32±4.83 μg/m3, which accounted for 32.1% of the PM2.5 concentration. The water-soluble components of PM2.5 and gaseous precursors showed obvious diurnal variation, with the increase of inorganic ion concentrations at night and the decrease of inorganic ion concentrations during the day after reaching their peak in the morning. The average SOR and NOR were 0.55 and 0.042, indicating that there was an obvious secondary transformation process of sulfate, but not of nitrate, which might be accompanied by the formation of nitrate and the decomposition of NH4NO3. The result of positive matrix factorization (PMF) indicated that there were five main contribution sources of water-soluble ions in PM2.5, which were fossil fuel combustion source and industry (36%), secondary sulfate (27%), biomass combustion (18%), secondary nitrate (16%) and sea salt (3%). Related Articles | Metrics | Comments（0）