Dynamic Behavior of Impacting Droplet on the Edges of Different Wettability Surface.

The dynamic behavior of impacting droplet shearing by the surface edge with different wettabilities is complicated and has great significance for engineering application. The morphological evolution of droplet with various Weber numbers (We) and wettability impacting on the edge of square substrate is investigated by high-speed photography. Moreover, the effects of the contact angle (α) and Weber numbers (We) on the shear breaking process of droplets are obtained. There are three types morphological evolution of impacting droplet are observed experimentally, including unbroken, tensile breakup, and shear breakup. Contact angle and Weber number have been proved to be the significant factors affecting the type of droplet morphological evolution. Meanwhile, the critical Weber number of different types are obtained quantitatively. Moreover, as α increases, the critical Weber numbers for breakup increase. In the shear breakup process, the mass ratio between the droplets remaining on the substrate and the initial droplets is maintained at 50%. Particularly, a reliable prediction model for the spreading of droplet impacting the side wall is proposed and compared with the experimental data. Overall, this study provides new direction and guidance for exploring droplet breakup kinetics.

The Roles of Segments and Tone in Mandarin Lexical Processing: An ERP Study.

BACKGROUNDS: Segments and tone are important sub-syllabic units that play large roles in lexical processing in tonal languages. However, their roles in lexical processing remain unclear, and the event-related potential (ERP) technique will benefit the exploration of the cognitive mechanism in lexical processing. METHODS: The high temporal resolution of ERP enables the technique to interpret rapidly changing spoken language performances. The present ERP study examined the different roles of segments and tone in Mandarin Chinese lexical processing. An auditory priming experiment was designed that included five types of priming stimuli: consonant mismatch, vowel mismatch, tone mismatch, unrelated mismatch, and identity. Participants were asked to judge whether the target of the prime-target pair was a real Mandarin disyllabic word or not. RESULTS: Behavioral results including reaction time and response accuracy and ERP results were collected. Results were different from those of previous studies that showed the dominant role of consonants in lexical access in mainly non-tonal languages like English. Our results showed that consonants and vowels play comparable roles, whereas tone plays a less important role than do consonants and vowels in lexical processing in Mandarin. CONCLUSIONS: These results have implications for understanding the brain mechanisms in lexical processing of tonal languages.

E2F1 interactive with BRCA1 pathway induces HCC two different small molecule metabolism or cell cycle regulation via mitochondrion or CD4+T to cytosol.

Breast cancer 1 (BRCA1) and E2F transcription factor 1 (E2F1) are related to metabolism and cell cycle regulation. However, the corresponding mechanism is not clear in HCC. High BRCA1 direct pathway was constructed with 11 molecules from E2F1 feedback-interactive network in HCC by GRNInfer based on 39 Pearson mutual positive corelation CC ≥0.25 molecules with E2F1. Integration of GRNInfer with GO, KEGG, BioCarta, GNF_U133A, UNIGENE_EST, Disease, GenMAPP databases by DAVID and MAS 3.0, E2F1 feedback-interactive BRCA1 indirect mitochondrion to cytosol pathway was identified as upstream LAPTM4B activation, feedback UNG, downstream BCAT1-HIST1H2AD-TK1 reflecting protein, and DNA binding with enrichment of small molecule metabolism; The corresponding BRCA1 indirect membrane to cytosol pathway as upstream CCNB2-NUSAP1 activation, feedback TTK-HIST1H2BJ-CENPF, downstream MCM4-TK1 reflecting ATP, and microtubule binding with enrichment of CD4+T-related cell cycle regulation in HCC. Therefore, we propose that E2F1 interactive with BRCA1 pathway induces HCC two different small molecule metabolism or cell cycle regulation via mitochondrion or CD4+T to cytosol. Knowledge analysis demonstrates our E2F1 feedback-interactive BRCA1 pathway wide disease distribution and reflects a novel common one of tumor and cancer.

Low glucose transporter SLC2A5-inhibited human normal adjacent lung adenocarcinoma cytoplasmic pro-B cell development mechanism network.

Solute carrier family 2 (facilitated glucose/fructose transporter) member 5 (SLC2A5)-inhibited seven different molecular Pearson mutual-positive-correlation networks constructed by 24 overlapping molecules from 368 GRNInfer and 34 Pearson under SLC2A5 CC ≤-0.25 in low human normal adjacent tissues were compared with high lung adenocarcinoma. Based on GO, KEGG, GenMAPP, BioCarta, and disease databases, our result showed that low SLC2A5-inhibited network included Golgi apparatus of AP1M2_1; cell cycle of CUL7, SAC3D1; protein amino acid dephosphorylation of STYXL1; pro-B cell-cell differentiation of SOX4_3; and FAD biosynthesis of FLAD1. Thus, we propose low glucose transporter SLC2A5-inhibited human normal adjacent lung adenocarcinoma cytoplasmic pro-B cell development mechanism network through repression of protein amino acid dephosphorylation to FAD biosynthesis.

BRCA1-mediated inflammation and growth activated & inhibited transition mechanisms between no-tumor hepatitis/cirrhotic tissues and HCC.

To understand breast cancer 1 early onset (BRCA1)-mediated inflammation and growth activated and inhibited transition mechanisms between no-tumor hepatitis/cirrhotic tissues (HBV or HCV infection) and human hepatocellular carcinoma (HCC), BRCA1-activated different complete (all no positive correlation, Pearson correlation coefficient <0.25) and uncomplete (partly no positive correlation except BRCA1, Pearson <0.25) networks were identified in higher HCC compared with lower no-tumor hepatitis/cirrhotic tissues (HBV or HCV infection) from the corresponding BRCA1-stimulated (Pearson ≥0.25) or inhibited (Pearson ≤-0.25) overlapping molecules of Pearson and GRNInfer, respectively. This result was verified by the corresponding scatter matrix. As visualized by GO, KEGG, GenMAPP, BioCarta, and disease database integration, we proposed mainly that BRCA1-stimulated different complete network was involved in BRCA1 activation with integral to membrane killer cell lectin-like receptor C to nucleus interferon regulatory factor 5-induced inflammation, whereas the corresponding inhibited network participated in BRCA1 repression with matrix roundabout axon guidance receptor homolog 1 to plasma membrane versican-induced growth in lower no-tumor hepatitis/cirrhotic tissues (HBV or HCV infection). However, BRCA1-stimulated network contained BRCA1 activation with endothelium-specific to lysosomal transmembrane and carbamoyl synthetase to tastin, histone cluster and cyclin-induced growth, whereas the corresponding inhibited different complete network included BRCA1 repression with ovalbumin, thyroid stimulating hormone beta and Hu antigen C to cytochrome P450 to transducin-induced inflammation in higher HCC. Our BRCA1 different networks were verified by BRCA1-activated or -inhibited complete and uncomplete networks within and between no-tumor hepatitis/cirrhotic tissues (HBV or HCV infection) or (and) HCC.

AGR2-mediated lung adenocarcinoma metastasis novel mechanism network through repression with interferon coupling cytoskeleton to steroid metabolism-dependent humoral immune response.

7 anterior gradient homolog 2 (AGR2)-inhibited different molecular mutual positive correlation network was constructed in lung adenocarcinoma compared with human normal adjacent tissues by 17 overlapping molecules of 358 GRNInfer and 19 Pearson (AGR2 CC⩽-0.25). Based on GO, KEGG, GenMAPP, BioCarta and disease databases, we determined AGR2-mediated lung adenocarcinoma metastasis through repression with cytoskeleton of MAST1; steroid metabolism of SOAT2; humoral immune response of POU2AF1; interferon alpha-inducible of IFI6; immunoglobulin of IGKC_3, CTA_246H3.1. Thus we proposed AGR2-mediated lung adenocarcinoma metastasis novel mechanism network through repression with interferon coupling cytoskeleton to steroid metabolism-dependent humoral immune response.

An ERP study on the late stage of Chinese metaphor processing.

Psycholinguistic models of metaphor processing remain a subject of debate. A prime-probe design using Chinese materials with a specific time span (300 ms) was applied to test the mechanisms of metaphor processing. Conventional and familiarized metaphors were designed as primes, followed by a probe word semantically related to the prime metaphor (MT), a probe word related to the literal meaning of the final word of the prime metaphor (LT), control/unrelated probe word (UT), or non-word. Event-related potentials (ERPs) elicited by the probes were recorded to examine metaphor processing. In N400, results revealed that UT and LT elicited significantly more negative waveforms than MT in both primes. MTs and LTs showed no difference between conventional and familiarized metaphors, suggesting that metaphorical meaning may be accessed directly, regardless of whether conventional or familiarized metaphors. The results were generally compatible with the direct processing model.

Lexical pathway from L2 to L1 activation in intermediate proficient bilinguals: behavioral and ERP evidence.

Numerous studies have demonstrated that second language (L2) comprehension is often accompanied by activations in the first language (L1). Using both behavioral measurement and event-related potential (ERP), this study conducted two experiments to investigate whether a direct activation pathway exists from L2 lexical representation to L1 lexical representation (the lexical pathway) in intermediate proficient bilinguals. In Experiment 1, we designed a vowel letter search task on English word pairs, which enables bilinguals to prevent semantic priming in the first 300 ms processing stage after the words' onset. In Experiment 2, Mandarin-English bilinguals were recruited to complete this task on English word pairs with occasional first character repetition between the Chinese counterparts of a word pair. Results showed a significant main effect within both the P200 and N400 time windows, indicating the activation of bilinguals' L1 lexical representation during these intervals. However, the main effect of semantic relatedness was only significant in the N400 time window. These results suggest that bilinguals can activate their L1 lexical representation directly before engaging in conceptual representation. This finding supported a lexical pathway of activation from L2 lexical representation to L1 lexical representation during visual-word recognition in intermediate proficient bilinguals.

Influence of flavor information on visual search: Attentional capture by and suppression of flavor-associated colors.

Numerous studies have demonstrated the impact of flavor cues on visual search, yet the underlying mechanisms remain elusive. In this experiment, we used event-related potentials (ERPs) to examine whether, and if so, how flavor information could lead to attentional capture by, and suppression of, flavor-associated colors. The participants were asked to taste certain flavored beverages and subsequently complete a shape-based visual search task, while their neural activities were simultaneously recorded. The behavioral results revealed that the participants made slower responses when a distractor in the flavor-associated color (DFAC) was present, suggesting an attentional bias toward the flavor-associated color. The ERP results revealed that the N2pc was detected if the target and the DFAC were shown in the same visual field (e.g. both target and DFCA on the right side of the screen), when the pairings between flavor cues and target colors were incongruent. However, the N2pc was not observed if the target and the DFAC were shown in the opposite visual fields (e.g. target on the right and DFCA on the left side of the screen) for the incongruent color-flavor pairings. Moreover, the distractor positivity (Pd) was observed if the target and the DFAC were shown in the opposite visual field for the congruent color-flavor pairings. These results suggest that both attentional capture and suppression are involved in the influence of flavor information on visual search. Collectively, these findings provide initial electrophysiological evidence on the mechanisms of the crossmodal influence of flavor cues on visual search.

PTHLH coupling upstream negative regulation of fatty acid biosynthesis and Wnt receptor signal to downstream peptidase activity-induced apoptosis network in human hepatocellular carcinoma by systems-theoretical analysis.

Studies were done on the analysis of biological processes in the same high expression (fold change ≥ 2) PTHLH-activated feedback negative regulation-mediated apoptosis gene ontology (GO) network of human hepatocellular carcinoma (HCC) compared with the corresponding low expression activated GO network of no-tumor hepatitis/cirrhotic tissues [hepatitis B virus (HBV) or hepatitis C virus (HCV) infection]. We proposed PTHLH-activated network that upstream included the regulation of apoptosis, signal transduction resulting in induction of apoptosis, signal transduction by p53 class mediator resulting in transcription of p21 class mediator, negative regulation of centriole replication, negative regulation of fatty acid biosynthesis, negative regulation of Wnt receptor signaling pathway, anaphase-promoting complex-dependent proteasomal ubiquitin-dependent protein catabolism, apoptosis, induction of apoptosis, and negative regulation of phosphorylation. Downstream-network negative regulation of peptidase activity, anaphase-promoting complex-dependent proteasomal ubiquitin-dependent protein catabolism, apoptosis, induction of apoptosis and negative regulation of phosphorylation, as a result of coupling upstream negative regulation of fatty acid biosynthesis and Wnt receptor signal to downstream peptidase activity-induced apoptosis in HCC. Our hypothesis was verified by the different PTHLH-activated feedback negative regulation-mediated apoptosis GO network of HCC compared with the corresponding inhibited GO network of no-tumor hepatitis/cirrhotic tissues, or the same compared with the corresponding inhibited GO network of HCC. PTHLH coupling upstream negative regulation of fatty acid biosynthesis and Wnt receptor signal to downstream peptidase activity-induced apoptosis network was constructed that upstream BRCA1, DKK1, BUB1B activated PTHLH, and downstream PTHLH-activated CST6, BUB1B, NTN1, PHLDA2 in HCC from GEO data set using gene regulatory network inference method and our programing.

P-glycoprotein (ABCB1) inhibited network of mitochondrion transport along microtubule and BMP signal-induced cell shape in chimpanzee left cerebrum by systems-theoretical analysis.

We constructed the significant low-expression P-glycoprotein (ABCB1) inhibited transport and signal network in chimpanzee compared with high-expression (fold change ≥2) the human left cerebrum in GEO data set, by using integration of gene regulatory activated and inhibited network inference method with gene ontology (GO) analysis. Our result showed that ABCB1 transport and signal upstream network RAB2A inhibited ABCB1, and downstream ABCB1-inhibited SMAD1_2, NCK2, SLC25A46, GDF10, RASGRP1, EGFR, LRPPRC, RASSF2, RASA4, CA2, CBLB, UBR5, SLC25A16, ITGB3BP, DDIT4, PDPN, RAB2A in chimpanzee left cerebrum. We obtained that the different biological processes of ABCB1 inhibited transport and signal network repressed carbon dioxide transport, ER to Golgi vesicle-mediated transport, folic acid transport, mitochondrion transport along microtubule, water transport, BMP signaling pathway, Ras protein signal transduction, transforming growth factor beta receptor signaling pathway in chimpanzee compared with the inhibited network of the human left cerebrum, as a result of inducing inhibition of mitochondrion transport along microtubule and BMP signal-induced cell shape in chimpanzee left cerebrum. Our hypothesis was verified by the same and different biological processes of ABCB1 inhibited transport and signal network of chimpanzee compared with the corresponding activated network of chimpanzee and the human left cerebrum, respectively.

Activated PTHLH coupling feedback phosphoinositide to G-protein receptor signal-induced cell adhesion network in human hepatocellular carcinoma by systems-theoretic analysis.

Studies were done on analysis of biological processes in the same high expression (fold change ≥2) activated PTHLH feedback-mediated cell adhesion gene ontology (GO) network of human hepatocellular carcinoma (HCC) compared with the corresponding low expression activated GO network of no-tumor hepatitis/cirrhotic tissues (HBV or HCV infection). Activated PTHLH feedback-mediated cell adhesion network consisted of anaphase-promoting complex-dependent proteasomal ubiquitin-dependent protein catabolism, cell adhesion, cell differentiation, cell-cell signaling, G-protein-coupled receptor protein signaling pathway, intracellular transport, metabolism, phosphoinositide-mediated signaling, positive regulation of transcription, regulation of cyclin-dependent protein kinase activity, regulation of transcription, signal transduction, transcription, and transport in HCC. We proposed activated PTHLH coupling feedback phosphoinositide to G-protein receptor signal-induced cell adhesion network. Our hypothesis was verified by the different activated PTHLH feedback-mediated cell adhesion GO network of HCC compared with the corresponding inhibited GO network of no-tumor hepatitis/cirrhotic tissues, or the same compared with the corresponding inhibited GO network of HCC. Activated PTHLH coupling feedback phosphoinositide to G-protein receptor signal-induced cell adhesion network included BUB1B, GNG10, PTHR2, GNAZ, RFC4, UBE2C, NRXN3, BAP1, PVRL2, TROAP, and VCAN in HCC from GEO dataset using gene regulatory network inference method and our programming.

Survivin (BIRC5) cell cycle computational network in human no-tumor hepatitis/cirrhosis and hepatocellular carcinoma transformation.

Survivin (BIRC5) relationship with tumor is presented in several papers. However, how the molecular network and interpretation concerning BIRC5 cell cycle between no-tumor hepatitis/cirrhosis and hepatocellular carcinoma (HCC) remains to be elucidated. Here, we constructed and analyzed significant higher expression gene BIRC5 activated and inhibited cell cycle network from HCC versus no-tumor hepatitis/cirrhosis patients (viral infection HCV or HBV) in GEO Dataset by combination of gene regulatory network inference method based on linear programming and decomposition procedure with the CapitalBio MAS 3.0 software based on the integration of public databases including Gene Ontology, KEGG, BioCarta, GenMapp, Intact, UniGene, OMIM, etc. Compared the same and different activated and inhibited BIRC5 network with GO analysis between no-tumor hepatitis/cirrhosis and HCC, our result showed BIRC5 cell cycle network weaker transcription factor activity in both no-tumor hepatitis/cirrhosis and HCC (1); stronger nucleus protein binding but weaker cytoplasm protein binding in no-tumor hepatitis/cirrhosis (2); stronger cytoplasm protein phosphatase binding but weaker ubiquitin-protein ligase activity in HCC (3). Therefore, we inferred BIRC5 cell cycle module less transcription from RNA polymerase II promoter in both no-tumor hepatitis/cirrhosis and HCC (4). We deduced BIRC5 cell cycle module different from more mitosis but less complex-dependent proteasomal ubiquitin-dependent protein catabolism as a result increasing cell division and cell numbers in no-tumor hepatitis/cirrhosis to more protein amino acid autophosphorylation but less negative regulation of ubiquitin ligase activity during mitotic cell cycle as a result increasing growth and cell volume in HCC (5).

MYBPC1 computational phosphoprotein network construction and analysis between frontal cortex of HIV encephalitis (HIVE) and HIVE-control patients.

MYBPC1 computational phosphoprotein network construction and analysis of frontal cortex of HIV encephalitis (HIVE) was very useful to identify novel markers and potential targets for prognosis and therapy. Based on integrated gene regulatory network infer method by linear programming and a decomposition procedure with analysis of the significant function cluster using kappa statistics and fuzzy heuristic clustering from the database for annotation, visualization, and integrated discovery, we identified and constructed significant molecule MYBPC1 phosphoprotein network from 12 frontal cortex of HIVEcontrol patients and 16 HIVE in the same GEO Dataset GDS1726. Our result verified MYBPC1 phosphoprotein module only in the upstream of frontal cortex of HIVEcontrol patients (CREB5, MAPKAPK3 inhibition), whereas in the upstream of frontal cortex of HIVE (CREB5, ZC3HAV1 activation; ROR1 inhibition) and downstream (MAPKAPK3 activation; CFDP1, PDCD4, RBBP6 inhibition). Importantly, we determined that MYBPC1 phosphoprotein cluster of HIVE was involved in signal transduction, transferase, post-translational protein modification, developmental process and glycoprotein (only in HIVE terms), the condition was vital to inflammation and cognition impairment of HIVE. Our result demonstrated that common terms in both HIVE-control patients and HIVE included phosphoprotein, organelle, response to stimulus, nucleic acid binding, primary metabolic process, and biological regulation, and these terms were more relative to inflammation and cognition impairment, therefore, we deduced the stronger MYBPC1 phosphoprotein network in HIVE. It would be necessary of the stronger MYBPC1 phosphoprotein function to inflammation and cognition impairment of HIVE.

Semantic and Syntactic Processing During Comprehension: ERP Evidence From Chinese QING Structure.

Previous studies used BA and BEI structures as stimuli to infer that syntax-first models seemed not applicable in Chinese. However, there were inconsistent results of both within same structures and between different structures. Since sentence structures of stimuli were non-canonical as well as lacking wide representativeness in Chinese, we examined the processing mechanism of a more representative structure in Chinese, QING (QING + NP1 + V + NP2) structure in the current study. Four conditions, including correct sentences (CORRECT), semantic-violated sentences (SEMANTIC), syntactic-violated sentences (SYNTACTIC), and combined violated sentences (COMBINED), were composed by manipulating the V between NP1 and NP2. Results with respect to three types of violation were as follows. In the initial phrase (100-300 ms), there existed an interaction between SEMANTIC consistency and the SYNTACTIC category. In the intermediate phrase (300-500 ms), the interaction continued with similar negative waves evoked by three types of violated sentences. In the final phrase (500-700 ms), both SYNTACTIC or COMBINED evoked obvious negative waves. The current research of Qing structure provided new evidence for the processing mechanism of Chinese sentence patterns. Specifically, we found that the interactive model rather than the syntax-first model may apply to the processing of this specific structure of Chinese sentences and compared the results with those reported in previous studies that examined other types of sentence structures.

Interaction between Phonological and Semantic Processes in Visual Word Recognition using Electrophysiology.

Controversies have always existed in research related to reading abilities; on whether printed words are perceived in a feedforward manner based on orthographic information after which, other representations, such as phonology and semantics are activated, or whether these are fully interactive and high-level semantic information affects early processing. An interference paradigm was implemented in the presented protocol of phonological and semantic judgment tasks that utilized the same precede-target pairs to explore the relative order of phonological and semantic activation. The high- and low-frequency target words were preceded with three conditions: semantically related, phonological-related (homophones), or unrelated. The results showed that the induced P200 component of low-frequency word pairs was significantly greater than high-frequency words in both the semantic and phonological tasks. In addition, both the homophones in the semantic task and the semantically related pairs in the phonological task caused reduction in N400 when compared to the the control condition, word frequency-independently. It is worth noting that for the low-frequency pairs in the phonological judgment task, the P200 released by the semantically related word pairs was significantly larger than that in the control condition. Overall, semantic processing in phonological tasks and phonological processing in semantic tasks were found in both high- and low-frequency words, suggesting that the interaction between semantics and phonology may operate in a task-independent manner. However, the specific time this interaction occurred may have been affected by the task and frequency.

Bilingual Brains Learn to Use L2 Alliterations Covertly like Poets: Brain ERP Evidence.

Bilinguals were documented to access their native or first language (L1) during comprehension of their second languages (L2). However, it is uncertain whether they can access L2 when reading their first language. This study used the event-related potential (ERP) technique to demonstrate the implicit and unconscious access to English words when Chinese-English bilinguals read words in Chinese, their native language. The participants were asked to judge whether the Chinese words presented in pairs were semantically related or not, meanwhile unconscious of the occasional alliteration (repetition of the first phoneme) if the Chinese words were translated into English. While the concealed prime in English translations failed to affect the reaction time, the alliteration significantly modulated N400 among advanced English learners, especially for semantically unrelated word pairs. Critically, this modulation effect was discrepant between bilinguals with high-level and normal-level English proficiency. These results indicate that L2 activation is an unconscious correlate of native-language processing depending on L2 proficiency.

An ERP Study on the Role of Phonological Processing in Reading Two-Character Compound Chinese Words of High and Low Frequency.

Unlike in English, the role of phonology in word recognition in Chinese is unclear. In this event-related potential experiment, we investigated the role of phonology in reading both high- and low-frequency two-character compound Chinese words. Participants executed semantic and homophone judgment tasks of the same precede-target pairs. Each pair of either high- or low-frequency words were either unrelated (control condition) or related semantically or phonologically (homophones). The induced P200 component was greater for low- than for high-frequency word-pairs both in semantic and phonological tasks. Homophones in the semantic judgment task and semantically-related words in the phonology task both elicited a smaller N400 than the control condition, word frequency-independently. However, for low-frequency words in the phonological judgment task, it was found that the semantically related pairs released a significantly larger P200 than the control condition. Thus, the semantic activation of both high- and low-frequency words may be no later than phonological activation.

Delving Into the Working Mechanism of Prediction in Sentence Comprehension: An ERP Study.

The present study aims to delineate the working mechanism of prediction in sentence comprehension, by disentangling the influence of the facilitated general memory retrieval from the coexistent influence of the predicted language-specific semantic and/or syntactic information for the first time. The results support that prediction might influence the downstream cognitive processing in two aspects: (1) the pre-activated information facilitates the retrieval of a matched input in memory and, (2) the pre-activated information interacts with higher-level semantic/syntactic processing. More importantly, the present findings suggest that these two types of influences seem to occur at different stages of sentence comprehension: the facilitated memory retrieval of the input modulates N400 amplitude and the latency of post-N400 late central-parietal positivity/P600, while the predicted semantic/syntactic information and/or their interactions modulate the amplitude of the late positivity. The present findings would be helpful for interpreting the underlying mechanism of observed effects in prediction studies.

Analysis and Prediction of Methane Invasion Distance Considering Real Ground Boundary.

Natural gas has become a global energy consumption hotspot because of its large reserves and clean combustion. Due to soil corrosion, construction damage, and natural disasters, leakage accidents of buried natural gas pipelines often occur. In this paper, the steady simulation method was used to study the methane invasion limit state (MILS) and the methane invasion limit distance (MILD) under the conditions of hardened surface ground (HSG), unhardened surface ground (UHSG), and semihardened surface ground (SHSG), and the transient simulation of methane invasion distance (MID) under the condition of HSG with the largest MILD was carried out. The results showed that regardless of ground conditions, with the increase of leakage time, the diffusion range of methane in soil will not increase all the time, and there was a limit state (MILS). The distribution range and concentration of methane in the soil under HSG condition were the largest, followed by the SHSG condition, and the UHSG condition was the smallest. When the ground condition changed from UHSG to HSG, the MILD increased from 3.41 to 9.32 m. The HSG condition will increase the MILD and the range of dangerous areas. The buried depth of the pipeline had a serious impact on the MILD. When the buried depth of the pipeline increased from 0.3 to 1.5 m, the MILD increased from 1.75 to 3.49 m under the condition of UHSG and exceeded 10 m under the condition of HSG. The average error of the MID prediction model was 2.37% under the condition of HSG, which can accurately predict the leakage of buried pipeline. The MID provides a reference for the layout of urban underground gas leakage monitoring points. The MILD can provide guidance for the safe distance between natural gas pipeline and structures in the design code of natural gas pipeline.