Pub Date : 2024-12-01DOI: 10.1016/j.enmf.2023.09.004
Zhi-xiang Zhang , Yi-lin Cao , Chao Chen , Lin-yuan Wen , Yi-ding Ma , Bo-zhou Wang , Ying-zhe Liu
In this study, machine learning (ML)-assisted regression modeling was conducted to predict the thermal decomposition temperatures and explore the factors that correlate with the thermal stability of energetic materials (EMs). The modeling was performed based on a dataset consisting of 885 various compounds using linear and nonlinear algorithms. The tree-based models established demonstrated acceptable predictive abilities, yielding a low mean absolute error (MAE) of 31°C. By analyzing the dataset through hierarchical classification, this study insightfully identified the factors affecting EMs’ thermal decomposition temperatures, with the overall accuracy improved through targeted modeling. The SHapley Additive exPlanations (SHAP) analysis indicated that descriptors such as BCUT2D, PEOE_VSA, MolLog_P, and TPSA played a significant role, demonstrating that the thermal decomposition process is influenced by multiple factors relating to the composition, electron distribution, chemical bond properties, and substituent type of molecules. Additionally, descriptors such as Carbon_contents and Oxygen_Balance proposed for characterizing EMs showed strong linear correlations with thermal decomposition temperatures. The trends of their SHAP values indicated that the most suitable ranges of Carbon_contents and Oxygen_Balance were 0.2∼0.35 and −65∼−55, respectively. Overall, the study shows the potential of ML models for decomposition temperature prediction of EMs and provides insights into the characteristics of molecular descriptors.
{"title":"Machine learning-assisted quantitative prediction of thermal decomposition temperatures of energetic materials and their thermal stability analysis","authors":"Zhi-xiang Zhang , Yi-lin Cao , Chao Chen , Lin-yuan Wen , Yi-ding Ma , Bo-zhou Wang , Ying-zhe Liu","doi":"10.1016/j.enmf.2023.09.004","DOIUrl":"10.1016/j.enmf.2023.09.004","url":null,"abstract":"<div><div>In this study, machine learning (ML)-assisted regression modeling was conducted to predict the thermal decomposition temperatures and explore the factors that correlate with the thermal stability of energetic materials (EMs). The modeling was performed based on a dataset consisting of 885 various compounds using linear and nonlinear algorithms. The tree-based models established demonstrated acceptable predictive abilities, yielding a low mean absolute error (<em>MAE</em>) of 31°C. By analyzing the dataset through hierarchical classification, this study insightfully identified the factors affecting EMs’ thermal decomposition temperatures, with the overall accuracy improved through targeted modeling. The SHapley Additive exPlanations (SHAP) analysis indicated that descriptors such as BCUT2D, PEOE_VSA, MolLog_P, and TPSA played a significant role, demonstrating that the thermal decomposition process is influenced by multiple factors relating to the composition, electron distribution, chemical bond properties, and substituent type of molecules. Additionally, descriptors such as Carbon_contents and Oxygen_Balance proposed for characterizing EMs showed strong linear correlations with thermal decomposition temperatures. The trends of their SHAP values indicated that the most suitable ranges of Carbon_contents and Oxygen_Balance were 0.2∼0.35 and −65∼−55, respectively. Overall, the study shows the potential of ML models for decomposition temperature prediction of EMs and provides insights into the characteristics of molecular descriptors.</div></div>","PeriodicalId":34595,"journal":{"name":"Energetic Materials Frontiers","volume":"5 4","pages":"Pages 274-282"},"PeriodicalIF":3.3,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135348903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01DOI: 10.1016/j.enmf.2024.01.002
Luciana Amorim da Silva, Gabriel Monteiro-de-Castro, Erick Braga Ferrão Galante, Itamar Borges Jr, Aline Cardoso Anastácio
<div><div>The main challenge in designing new energetic materials is to find a good balance between four seemingly incompatible requirements, namely, high-energy content, low sensitivity, low production costs and less-polluting content. Fused nitrogen heterocycles of imidazole and pyrimidine, such as acyclovir and guanine, may offer interesting features due to the combination of a coplanar framework and a large conjugate system, which contribute to a reduced sensitivity, and a number of energetic bonds that can be increased by the introduction of explosophore substituents. In this work, to evaluate the potential of acyclovir and guanine derivatives as energetic materials, density functional theory (DFT) calculations were carried out to investigate the influence of the type and position of the explosophore substituent groups –<span><math><mrow><mi>N</mi><msub><mi>O</mi><mn>2</mn></msub></mrow></math></span>, –<span><math><mrow><mi>N</mi><mi>H</mi><mi>N</mi><msub><mi>O</mi><mn>2</mn></msub></mrow></math></span>, –<span><math><mrow><msub><mi>N</mi><mn>3</mn></msub></mrow></math></span>, –<span><math><mrow><mi>O</mi><mi>N</mi><msub><mi>O</mi><mn>2</mn></msub></mrow></math></span>, –<span><math><mrow><mi>C</mi><mi>N</mi></mrow></math></span>, <span><math><mrow><mo>−</mo><mi>N</mi><mo>=</mo><mi>N</mi><mo>−</mo><mtext>,</mtext></mrow></math></span> and <span><math><mrow><mo>−</mo><mi>N</mi><mo>=</mo><mi>N</mi><mrow><mo>(</mo><mi>O</mi><mo>)</mo></mrow><mo>−</mo></mrow></math></span> on the energetic properties and chemical reactivity of 91 acyclovir- and guanine-based molecules, including thirty one nitramines, three nitroheterocycles, seventeen azides, seventeen nitrate esters, seventeen nitriles, three azo and three azoxy compounds. Several molecular properties were computed, including the chemical reactivity, the heat of formation and the detonation velocities and pressures using semiempirical equations. Among the molecules with no bridge groups, we found that, except for cyano group, position 4 were the most stable for acyclovir derivatives, whereas, except for the azido group, position 2 and 5 provided the most stable compounds for guanine derivatives. Among the bridged derivatives, depending on the molecule and positions, the nitrate esters and the nitro derivatives were more stable. In comparison with the parent compounds, calculations showed that the heat of formation (HOF) increased the most with azido and cyano groups, the density increased substantially with nitrate esters, nitro and nitramino groups, and the detonation velocities and pressures increased the most with nitrate ester, nitro and nitramino groups. Although azo groups resulted in higher HOFs than azoxy groups, azoxy derivatives showed superior values in terms of density, heat of maximum detonation, detonation velocity and pressure. Four nitrate esters (GD134, GD245, AZOXYGD13 and AZOXYGD25) displayed higher values of detonation velocity and pressure than RDX. The designed nitramin
{"title":"A density functional theory investigation of the substituent effect on acyclovir and guanine derivatives for applications on energetic materials","authors":"Luciana Amorim da Silva, Gabriel Monteiro-de-Castro, Erick Braga Ferrão Galante, Itamar Borges Jr, Aline Cardoso Anastácio","doi":"10.1016/j.enmf.2024.01.002","DOIUrl":"10.1016/j.enmf.2024.01.002","url":null,"abstract":"<div><div>The main challenge in designing new energetic materials is to find a good balance between four seemingly incompatible requirements, namely, high-energy content, low sensitivity, low production costs and less-polluting content. Fused nitrogen heterocycles of imidazole and pyrimidine, such as acyclovir and guanine, may offer interesting features due to the combination of a coplanar framework and a large conjugate system, which contribute to a reduced sensitivity, and a number of energetic bonds that can be increased by the introduction of explosophore substituents. In this work, to evaluate the potential of acyclovir and guanine derivatives as energetic materials, density functional theory (DFT) calculations were carried out to investigate the influence of the type and position of the explosophore substituent groups –<span><math><mrow><mi>N</mi><msub><mi>O</mi><mn>2</mn></msub></mrow></math></span>, –<span><math><mrow><mi>N</mi><mi>H</mi><mi>N</mi><msub><mi>O</mi><mn>2</mn></msub></mrow></math></span>, –<span><math><mrow><msub><mi>N</mi><mn>3</mn></msub></mrow></math></span>, –<span><math><mrow><mi>O</mi><mi>N</mi><msub><mi>O</mi><mn>2</mn></msub></mrow></math></span>, –<span><math><mrow><mi>C</mi><mi>N</mi></mrow></math></span>, <span><math><mrow><mo>−</mo><mi>N</mi><mo>=</mo><mi>N</mi><mo>−</mo><mtext>,</mtext></mrow></math></span> and <span><math><mrow><mo>−</mo><mi>N</mi><mo>=</mo><mi>N</mi><mrow><mo>(</mo><mi>O</mi><mo>)</mo></mrow><mo>−</mo></mrow></math></span> on the energetic properties and chemical reactivity of 91 acyclovir- and guanine-based molecules, including thirty one nitramines, three nitroheterocycles, seventeen azides, seventeen nitrate esters, seventeen nitriles, three azo and three azoxy compounds. Several molecular properties were computed, including the chemical reactivity, the heat of formation and the detonation velocities and pressures using semiempirical equations. Among the molecules with no bridge groups, we found that, except for cyano group, position 4 were the most stable for acyclovir derivatives, whereas, except for the azido group, position 2 and 5 provided the most stable compounds for guanine derivatives. Among the bridged derivatives, depending on the molecule and positions, the nitrate esters and the nitro derivatives were more stable. In comparison with the parent compounds, calculations showed that the heat of formation (HOF) increased the most with azido and cyano groups, the density increased substantially with nitrate esters, nitro and nitramino groups, and the detonation velocities and pressures increased the most with nitrate ester, nitro and nitramino groups. Although azo groups resulted in higher HOFs than azoxy groups, azoxy derivatives showed superior values in terms of density, heat of maximum detonation, detonation velocity and pressure. Four nitrate esters (GD134, GD245, AZOXYGD13 and AZOXYGD25) displayed higher values of detonation velocity and pressure than RDX. The designed nitramin","PeriodicalId":34595,"journal":{"name":"Energetic Materials Frontiers","volume":"5 4","pages":"Pages 293-308"},"PeriodicalIF":3.3,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139952275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01DOI: 10.1016/j.enmf.2024.07.001
Guan-chen Dong , Jia-lu Guan , Ling-hua Tan , Jing Lv , Xiao-na Huang , Guang-cheng Yang
1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) is a highly insensitive energetic material used in applications where extreme safety is required primarily. Ensuring the safe use of TATB as planned relies on research into intrinsic behavior under shock loading, which needs further investigation. Here, we study the shock response in oriented supercells of the highly anisotropic TATB based on reactive molecular dynamics simulations and multi-scale shock technique. Results demonstrate that the mechanical response primarily consists of adiabatic compression and plastic deformation. The system is more susceptible to be compressed rather than plastic deformed when shocked direction to the molecular layer at a 45° angle, resulting in the most obvious initial temperature increase. The chemical reaction pathways are similar in our simulations. Under shock loading, polymerization occurs first and then decomposition begins. However, the overall chemical kinetics response intensifies, as the angle between the shock direction and molecular layer decreases. Nonetheless, the rate of decomposition does not strictly correlate with shock direction. Moreover, clusters evolution shows different reactivity based on shock direction and velocity, which makes anisotropy weak at high shock velocity.
{"title":"Anisotropic shock response in oriented omnidirectional TATB supercells based on reactive molecular dynamics simulations","authors":"Guan-chen Dong , Jia-lu Guan , Ling-hua Tan , Jing Lv , Xiao-na Huang , Guang-cheng Yang","doi":"10.1016/j.enmf.2024.07.001","DOIUrl":"10.1016/j.enmf.2024.07.001","url":null,"abstract":"<div><div>1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) is a highly insensitive energetic material used in applications where extreme safety is required primarily. Ensuring the safe use of TATB as planned relies on research into intrinsic behavior under shock loading, which needs further investigation. Here, we study the shock response in oriented supercells of the highly anisotropic TATB based on reactive molecular dynamics simulations and multi-scale shock technique. Results demonstrate that the mechanical response primarily consists of adiabatic compression and plastic deformation. The system is more susceptible to be compressed rather than plastic deformed when shocked direction to the molecular layer at a 45° angle, resulting in the most obvious initial temperature increase. The chemical reaction pathways are similar in our simulations. Under shock loading, polymerization occurs first and then decomposition begins. However, the overall chemical kinetics response intensifies, as the angle between the shock direction and molecular layer decreases. Nonetheless, the rate of decomposition does not strictly correlate with shock direction. Moreover, clusters evolution shows different reactivity based on shock direction and velocity, which makes anisotropy weak at high shock velocity.</div></div>","PeriodicalId":34595,"journal":{"name":"Energetic Materials Frontiers","volume":"5 4","pages":"Pages 318-328"},"PeriodicalIF":3.3,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141770485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01DOI: 10.1016/j.enmf.2024.09.002
Hua-peng Liu , Qian-qian Wen , Wei Tang , Hong Wang , Xi-lin Yan
TATB-based polymer-bonded explosives (PBXs) exhibit intricate internal stress distributions due to crystal anisotropy. When diffraction techniques are employed to measure these internal residual stresses, it is critical to identify the discrepancy between the diffraction elastic constants (DEC) of particular crystal planes of a TATB-based PBX and the macroscopic elastic constant of the PBX. This study introduced various micromechanical models to describe the mechanical behavior of TATB-based PBXs, as well as assessing their accuracy in predicting the elastic properties of the PBXs and calculating the DECs of different crystal planes. Using in situ tensile experiments, this study obtained accurate DECs of the crystal plane of TATB-based PBXs and revised the residual stress measurements of the PBXs. The comparison between experimental results indicates that the two-phase and double-inclusion micromechanical models proposed in this study exhibit higher precision in predicting both the quasi-static mechanical properties of the PBXs and the DECs of the crystal plane. Furthermore, the DECs of the PBXs with high volume fractions of TATB are close to those of pure TATB crystals. Based on the established double-inclusion model, it can be inferred that the DECs of different crystal planes vary as a function of the TATB volume fraction. This study lays the foundation for profound analyses of the mechanical characteristics of TATB-based PBXs using diffraction techniques.
{"title":"Micromechanical models and experiments for diffractive elastic constants of TATB-based polymer-bonded explosives","authors":"Hua-peng Liu , Qian-qian Wen , Wei Tang , Hong Wang , Xi-lin Yan","doi":"10.1016/j.enmf.2024.09.002","DOIUrl":"10.1016/j.enmf.2024.09.002","url":null,"abstract":"<div><div>TATB-based polymer-bonded explosives (PBXs) exhibit intricate internal stress distributions due to crystal anisotropy. When diffraction techniques are employed to measure these internal residual stresses, it is critical to identify the discrepancy between the diffraction elastic constants (DEC) of particular crystal planes of a TATB-based PBX and the macroscopic elastic constant of the PBX. This study introduced various micromechanical models to describe the mechanical behavior of TATB-based PBXs, as well as assessing their accuracy in predicting the elastic properties of the PBXs and calculating the DECs of different crystal planes. Using in situ tensile experiments, this study obtained accurate DECs of the <span><math><mrow><mn>06</mn><mover><mn>2</mn><mo>‾</mo></mover></mrow></math></span> crystal plane of TATB-based PBXs and revised the residual stress measurements of the PBXs. The comparison between experimental results indicates that the two-phase and double-inclusion micromechanical models proposed in this study exhibit higher precision in predicting both the quasi-static mechanical properties of the PBXs and the DECs of the <span><math><mrow><mn>06</mn><mover><mn>2</mn><mo>‾</mo></mover></mrow></math></span> crystal plane. Furthermore, the DECs of the PBXs with high volume fractions of TATB are close to those of pure TATB crystals. Based on the established double-inclusion model, it can be inferred that the DECs of different crystal planes vary as a function of the TATB volume fraction. This study lays the foundation for profound analyses of the mechanical characteristics of TATB-based PBXs using diffraction techniques.</div></div>","PeriodicalId":34595,"journal":{"name":"Energetic Materials Frontiers","volume":"5 4","pages":"Pages 343-352"},"PeriodicalIF":3.3,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143230256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01DOI: 10.1016/j.enmf.2024.09.004
Bao-yue Guo , Ke-rong Ren , Xia-yin Ma , Gan Li , Cai-min Huang , Zhi-bin Li , Rong Chen
Metal/polymer reactive materials are inert under normal temperature and pressure conditions and possess a certain level of structural strength, allowing them to be fabricated into components such as fragments. However, under strong impact, they can undergo intense reactions and release a large amount of chemical energy. Al/PTFE is one of the most typical metal/polymer reactive materials. When reactive materials are used to make warhead fragments, they can deliver a significant amount of chemical energy to the target in addition to the kinetic energy damage. When used as the core of a PELE (Penetrator with Enhanced Lateral Efficiency) projectile, reactive materials can enhance the fragmentation of the projectile shell after penetrating the target, causing both physical and chemical damage. The reaction mechanism of these materials is complex, and it is difficult to directly monitor the chemical reaction process. The shock energy release process of reactive materials is different from the shock detonation process of traditional high explosives. Therefore, the existing reaction models describing the shock detonation process of explosives are not applicable to describe reactive substances. Consequently, understanding and describing the shock reaction characteristics of reactive materials on a macroscopic scale is crucial for promoting their engineering applications. Based on the plate impact experiments and thermal analysis of typical Al/PTFE reactive materials (with a mass ratio of Al to PTFE of 26.5:73.5), this paper proposes a phenomenological shock reaction model. The shock reaction model can describe the chemical reaction behavior of materials during shock compression. The mathematical expressions, programming implementation principles, and methods for obtaining model parameters of the shock reaction model are elaborated. At the same time, the shock reaction model is embedded into the material library of the LS-DYNA nonlinear dynamic simulation software as a secondary development. Numerical simulations of the behavior of Al/PTFE reactive materials in several typical applications are carried out. The results show that the shock reaction model can well describe the mechanical-thermal-chemical coupling behavior of Al/PTFE reactive materials under shock compression. This is of great significance for accelerating the engineering application of reactive materials in military fields such as weapon damage.
金属/聚合物反应材料在常温常压条件下是惰性的，并具有一定的结构强度，使其能够被制造成碎片等组件。然而，在强烈的冲击下，它们会发生激烈的反应，释放出大量的化学能。Al/PTFE是最典型的金属/聚合物反应材料之一。当使用反应性材料制造战斗部破片时，除了动能破坏外，还能向目标输送大量的化学能。反应材料作为PELE （Penetrator with Enhanced Lateral Efficiency）弹丸的核心材料，在穿透目标后可以增强弹壳的破片，造成物理和化学损伤。这些材料的反应机理复杂，难以对化学反应过程进行直接监测。反应物质的激波能量释放过程不同于传统烈性炸药的激波爆轰过程。因此，现有的描述炸药激波爆轰过程的反应模型不适用于描述反应性物质。因此，在宏观尺度上理解和描述反应材料的冲击反应特性对于促进其工程应用至关重要。基于典型Al/PTFE反应材料（Al/PTFE质量比为26.5:73.5）的板冲击实验和热分析，提出了一种现象学冲击反应模型。冲击反应模型可以描述材料在冲击压缩过程中的化学反应行为。阐述了冲击反应模型的数学表达式、编程实现原理和模型参数的获取方法。同时，将冲击反应模型作为二次开发嵌入到LS-DYNA非线性动态仿真软件的素材库中。对Al/PTFE反应材料在几种典型应用中的行为进行了数值模拟。结果表明，冲击反应模型能较好地描述Al/PTFE反应材料在冲击压缩下的力学-热-化学耦合行为。这对于加快反应材料在武器损伤等军事领域的工程应用具有重要意义。
{"title":"Shock reaction model for impact energy release behavior of Al/PTFE reactive material","authors":"Bao-yue Guo , Ke-rong Ren , Xia-yin Ma , Gan Li , Cai-min Huang , Zhi-bin Li , Rong Chen","doi":"10.1016/j.enmf.2024.09.004","DOIUrl":"10.1016/j.enmf.2024.09.004","url":null,"abstract":"<div><div>Metal/polymer reactive materials are inert under normal temperature and pressure conditions and possess a certain level of structural strength, allowing them to be fabricated into components such as fragments. However, under strong impact, they can undergo intense reactions and release a large amount of chemical energy. Al/PTFE is one of the most typical metal/polymer reactive materials. When reactive materials are used to make warhead fragments, they can deliver a significant amount of chemical energy to the target in addition to the kinetic energy damage. When used as the core of a PELE (Penetrator with Enhanced Lateral Efficiency) projectile, reactive materials can enhance the fragmentation of the projectile shell after penetrating the target, causing both physical and chemical damage. The reaction mechanism of these materials is complex, and it is difficult to directly monitor the chemical reaction process. The shock energy release process of reactive materials is different from the shock detonation process of traditional high explosives. Therefore, the existing reaction models describing the shock detonation process of explosives are not applicable to describe reactive substances. Consequently, understanding and describing the shock reaction characteristics of reactive materials on a macroscopic scale is crucial for promoting their engineering applications. Based on the plate impact experiments and thermal analysis of typical Al/PTFE reactive materials (with a mass ratio of Al to PTFE of 26.5:73.5), this paper proposes a phenomenological shock reaction model. The shock reaction model can describe the chemical reaction behavior of materials during shock compression. The mathematical expressions, programming implementation principles, and methods for obtaining model parameters of the shock reaction model are elaborated. At the same time, the shock reaction model is embedded into the material library of the LS-DYNA nonlinear dynamic simulation software as a secondary development. Numerical simulations of the behavior of Al/PTFE reactive materials in several typical applications are carried out. The results show that the shock reaction model can well describe the mechanical-thermal-chemical coupling behavior of Al/PTFE reactive materials under shock compression. This is of great significance for accelerating the engineering application of reactive materials in military fields such as weapon damage.</div></div>","PeriodicalId":34595,"journal":{"name":"Energetic Materials Frontiers","volume":"5 4","pages":"Pages 329-342"},"PeriodicalIF":3.3,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143230257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号