239 results on '"LI Lifeng"'
Search Results
2. Failure Analysis of Girth Weld Cracking in Gas Transmission Pipelines Subjected to Ground Subsidence and Traffic Loads.
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Li, Lifeng, Yan, Xiangzhen, Zhu, Lixia, Wu, Gang, and Zhang, Shuxin
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FUSION welding , *OXYACETYLENE welding & cutting , *WELDING defects , *FAILURE analysis , *FINITE element method , *PIPELINE failures , *PIPELINE inspection - Abstract
Girth welds are weak points in pipelines, and failures occur frequently. In a gas transmission pipeline, a girth weld experienced cracking, prompting a failure analysis using experimental methods and finite element analysis (FEA). Experimental results showed that X-ray non-destructive testing (NDT) revealed cracks, porosity, and lack of fusion in the girth weld. However, the hardness and microstructure of the material showed no abnormalities. During operation, the pipeline experienced an increase in soil cover and was subjected to ground subsidence and vehicle loads. Finite element analysis was conducted on the defective girth weld under different conditions, including varying soil cover depths, different levels of subsidence, and varying vehicle loads, to examine the pipeline's stress response. The results indicated that the combination of soil cover, subsidence, and vehicle loads led to pipeline failure, whereas none of these factors alone was sufficient to cause girth weld failure. To prevent such failures from occurring again, the following measures are recommended: strengthen on-site welding quality control of girth welds, conduct inspections for defects in girth welds of in-service pipelines, and promptly address any defects that exceed acceptable limits. [ABSTRACT FROM AUTHOR]
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- 2024
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3. Mechanisms of neural infiltration-mediated tumor metabolic reprogramming impacting immunotherapy efficacy in non-small cell lung cancer.
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Zheng, Yuanyuan, Li, Lifeng, Shen, Zhibo, Wang, Longhao, Niu, Xiaoyu, Wei, Yujie, Sun, Shilong, and Zhao, Jie
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NON-small-cell lung carcinoma , *METABOLIC reprogramming , *NERVE growth factor , *MOLECULAR biology , *TREATMENT effectiveness - Abstract
Background: Current evidence underlines the active role of neural infiltration and axonogenesis within the tumor microenvironment (TME), with implications for tumor progression. Infiltrating nerves stimulate tumor growth and dissemination by secreting neurotransmitters, whereas tumor cells influence nerve growth and differentiation through complex interactions, promoting tumor progression. However, the role of neural infiltration in the progression of non-small cell lung cancer (NSCLC) remains unclear. Methods: This study employs the techniques of immunohistochemistry, immunofluorescence, RNA sequencing, molecular biology experiments, and a murine orthotopic lung cancer model to deeply analyze the specific mechanisms behind the differential efficacy of NSCLC immunotherapy from the perspectives of neuro-tumor signal transduction, tumor metabolism, and tumor immunity. Results: This study demonstrates that nerve growth factor (NGF) drives neural infiltration in NSCLC, and 5-hydroxytryptamine (5-HT), which is secreted by nerves, is significantly elevated in tumors with extensive neural infiltration. Transcriptome sequencing revealed that 5-HT enhanced glycolysis in NSCLC cells. Pathway analysis indicated that 5-HT activated the PI3K/Akt/mTOR pathway, promoting tumor metabolic reprogramming. This reprogramming exacerbated immunosuppression in the TME. Neutralizing 5-HT-mediated metabolic reprogramming in tumor immunity enhanced the efficacy of PD-1 monoclonal antibody treatment in mice. Conclusions: The findings of this study provide a novel perspective on the crosstalk between nerves and lung cancer cells and provide insights into further investigations into the role of nerve infiltration in NSCLC progression. [ABSTRACT FROM AUTHOR]
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- 2024
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4. Phase‐only transmit beampattern synthesis with sparse arrays via alternating optimisation‐alternating direction of the multipliers method.
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Li, Lifeng, Liu, Xingang, Wang, Xiangrong, Hu, Mengkai, and Du, Yufeng
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ANTENNA radiation patterns , *ARRAY processing , *SIGNAL processing , *ALGORITHMS - Abstract
To get simultaneously sparse and constant modulus excitation to reduce the complexity of the array and the mutual effect of neighbouring elements, a novel algorithm via alternating optimisation‐alternating direction of the multipliers method is developed. This method uses the total transmitting power as the objective function to optimise the sparsity and the amplitude of excitation simultaneously. Numerical results are provided to verify its effectiveness. [ABSTRACT FROM AUTHOR]
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- 2024
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5. Altered functional connectivity of cerebellar subregions in male patients with obstructive sleep apnea: A resting-state fMRI study.
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Li, Lifeng, Liu, Yuting, Shu, Yongqiang, Liu, Xiang, Song, Yucheng, Long, Ting, Li, Kunyao, Xie, Wei, Zeng, Yaping, Zeng, Li, Huang, Ling, Liu, Yumeng, Deng, Yingke, Li, Haijun, and Peng, Dechang
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STATISTICAL correlation , *FUNCTIONAL connectivity , *INSULAR cortex , *T-test (Statistics) , *DATA analysis , *RESEARCH funding , *FISHER exact test , *MAGNETIC resonance imaging , *DESCRIPTIVE statistics , *SLEEP apnea syndromes , *COGNITION disorders , *LIMBIC system , *NEUROPSYCHOLOGICAL tests , *STATISTICS , *CEREBELLUM , *NEURORADIOLOGY , *PARIETAL lobe , *POLYSOMNOGRAPHY , *DATA analysis software , *COGNITION , *SYMPTOMS - Abstract
Purpose: Previous studies have demonstrated impaired cerebellar function in patients with obstructive sleep apnea (OSA), which is associated with impaired cognition. However, the effects of OSA on resting-state functional connectivity (FC) in the cerebellum has not been determined. The purpose of this study was to investigate resting-state FC of the cerebellar subregions and its relevance to clinical symptoms in patients with OSA. Methods: Sixty-eight patients with OSA and seventy-two healthy controls (HCs) were included in the study. Eight subregions of the cerebellum were selected as regions of interest, and the FC values were calculated for each subregion with other voxels. A correlation analysis was performed to examine the relationship between clinical and cognitive data. Results: Patients with OSA showed higher FC in specific regions, including the right lobule VI with the right posterior middle temporal gyrus and right angular gyrus, the right Crus I with the bilateral precuneus/left superior parietal lobule, and the right Crus II with the precuneus/right posterior cingulate cortex. Furthermore, the oxygen depletion index was negatively correlated with aberrant FC between the right Crus II and the bilateral precuneus / right posterior cingulate cortex in OSA patients (p = 0.004). Conclusion: The cerebellum is functionally lateralized and closely linked to the posterior default mode network. Higher FC is related to cognition, emotion, language, and sleep in OSA. Abnormal FC may offer new neuroimaging evidence and insights for a deeper comprehension of OSA-related alterations. This study reveals altered resting-state functional connectivity in the cerebellum (8 cerebellar subregions) of obstructive sleep apnea (OSA) patients. These changes correlate with cognitive, emotional, linguistic, and sleep deficits, suggesting functional impairments and compensation in the cerebellum of OSA patients. [ABSTRACT FROM AUTHOR]
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- 2024
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6. Abnormal dynamic functional connectivity and topological properties of cerebellar network in male obstructive sleep apnea.
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Li, Lifeng, Long, Ting, Liu, Yuting, Ayoub, Muhammad, Song, Yucheng, Shu, Yongqiang, Liu, Xiang, Zeng, Li, Huang, Ling, Liu, Yumeng, Deng, Yingke, Li, Haijun, and Peng, Dechang
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SLEEP apnea syndromes , *TOPOLOGICAL property , *FUNCTIONAL connectivity , *DEFAULT mode network , *LARGE-scale brain networks - Abstract
Purpose: To investigate dynamic functional connectivity (dFC) within the cerebellar‐whole brain network and dynamic topological properties of the cerebellar network in obstructive sleep apnea (OSA) patients. Methods: Sixty male patients and 60 male healthy controls were included. The sliding window method examined the fluctuations in cerebellum‐whole brain dFC and connection strength in OSA. Furthermore, graph theory metrics evaluated the dynamic topological properties of the cerebellar network. Additionally, hidden Markov modeling validated the robustness of the dFC. The correlations between the abovementioned measures and clinical assessments were assessed. Results: Two dynamic network states were characterized. State 2 exhibited a heightened frequency, longer fractional occupancy, and greater mean dwell time in OSA. The cerebellar networks and cerebrocerebellar dFC alterations were mainly located in the default mode network, frontoparietal network, somatomotor network, right cerebellar CrusI/II, and other networks. Global properties indicated aberrant cerebellar topology in OSA. Dynamic properties were correlated with clinical indicators primarily on emotion, cognition, and sleep. Conclusion: Abnormal dFC in male OSA may indicate an imbalance between the integration and segregation of brain networks, concurrent with global topological alterations. Abnormal default mode network interactions with high‐order and low‐level cognitive networks, disrupting their coordination, may impair the regulation of cognitive, emotional, and sleep functions in OSA. [ABSTRACT FROM AUTHOR]
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- 2024
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7. Head and Neck Malignant Paragangliomas: Experience from a Single Institution.
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Ding, Yiming, Li, Lifeng, Han, Demin, Wang, Shaozhong, and Chen, Xiaohong
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TREATMENT of rare diseases , *HEAD & neck cancer , *PARAGANGLIOMA , *IFOSFAMIDE , *TREATMENT effectiveness , *RETROSPECTIVE studies , *METASTASIS , *DACARBAZINE , *GENETIC mutation , *PACLITAXEL - Abstract
Objectives: To summarize the clinicopathological and genetic features of malignant paragangliomas in head and neck cancer and to explore the appropriate treatment options for this rare lesion. Methods: Six patients harboring head and neck malignant paraganglioma from Beijing Tongren Hospital were retrospectively reviewed. The clinicopathological characteristics, gene mutations, and prognosis of these patients were analyzed. Results: Of these 6 patients, 3 were male and 3 were female; 4 patients harbored malignant carotid body tumors, and two had malignant vagal paragangliomas. Three patients had cervical lymph node metastasis, two presented with lung and bone metastasis, and 1 had lung and liver metastasis. Of the 6 patients, four underwent surgical resection, and the other two patients denied surgery and instead received chemotherapy with paclitaxel, ifosfamide, and dacarbazine. These 2 patients with vagal paraganglioma received postoperative radiotherapy. All 6 patients are still alive at the present time, with a median follow-up time of 66 months. Positive Ki-67 expression in tumor tissue ranged from 1% to 40%. Genetic mutations in SDHD, SDHB, ATR, and MAP3K13 were identified in 4 patients. Conclusions: After comprehensive treatment, head and neck malignant paraganglioma can attain a favorable prognosis. Genetic mutations are commonly detected in patients with malignant paragangliomas. This study also identified mutations in ATR and MAP3K13 in these patients. [ABSTRACT FROM AUTHOR]
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- 2024
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8. Predictive value of CT and 18F-FDG PET/CT features on spread through air space in lung adenocarcinoma.
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Li, Haijun, Li, Lifeng, Liu, Yumeng, Deng, Yingke, Zhu, Yu, Huang, Ling, Long, Ting, Zeng, Li, Shu, Yongqiang, and Peng, Dechang
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Background: Lung adenocarcinoma, a leading cause of cancer-related mortality, demands precise prognostic indicators for effective management. The presence of spread through air space (STAS) indicates adverse tumor behavior. However, comparative differences between 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography(PET)/computed tomography(CT) and CT in predicting STAS in lung adenocarcinoma remain inadequately explored. This retrospective study analyzes preoperative CT and 18F-FDG PET/CT features to predict STAS, aiming to identify key predictive factors and enhance clinical decision-making. Methods: Between February 2022 and April 2023, 100 patients (108 lesions) who underwent surgery for clinical lung adenocarcinoma were enrolled. All these patients underwent 18F-FDG PET/CT, thin-section chest CT scan, and pathological biopsy. Univariate and multivariate logistic regression was used to analyze CT and 18F-FDG PET/CT image characteristics. Receiver operating characteristic curve analysis was performed to identify a cut-off value. Results: Sixty lesions were positive for STAS, and 48 lesions were negative for STAS. The STAS-positive was frequently observed in acinar predominant. However, STAS-negative was frequently observed in minimally invasive adenocarcinoma. Univariable analysis results revealed that CT features (including nodule type, maximum tumor diameter, maximum solid component diameter, consolidation tumor ratio, pleural indentation, lobulation, spiculation) and all 18F-FDG PET/CT characteristics were statistically significant difference in STAS-positive and STAS-negative lesions. And multivariate logistic regression results showed that the maximum tumor diameter and SUVmax were the independent influencing factors of CT and 18F-FDG PET/CT in STAS, respectively. The area under the curve of maximum tumor diameter and SUVmax was 0.68 vs. 0.82. The cut-off value for maximum tumor diameter and SUVmax was 2.35 vs. 5.05 with a sensitivity of 50.0% vs. 68.3% and specificity of 81.2% vs. 87.5%, which showed that SUVmax was superior to the maximum tumor diameter. Conclusion: The radiological features of SUVmax is the best model for predicting STAS in lung adenocarcinoma. These radiological features could predict STAS with excellent specificity but inferior sensitivity.Highlights: • Evaluated PET/CT and CT features for predicting STAS in lung adenocarcinoma. • SUVmax and maximum tumor diameter were independent influential factors for STAS(+) in lung adenocarcinoma. • SUVmax showed higher predictive efficacy than maximum tumor diameter. • Radiological characteristics may serve as noninvasive biomarkers for STAS prediction in lung adenocarcinoma. [ABSTRACT FROM AUTHOR]
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- 2024
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9. Sufficient conditions for interval-valued optimal control problems in admissible orders.
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Li, Lifeng and Zhang, Jianke
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LINEAR orderings , *EVOLUTIONARY algorithms - Abstract
This paper addresses the optimal control problems with an interval-valued objective function. We consider a type of total order relationships ≤ adm between two intervals. For each total order relationship, Kuhn–Tucker sufficient conditions for the optimal control problems with an interval-valued objective function are obtained. A numerical example is considered and solved. Kuhn–Tucker sufficient conditions provided under the total order relationship ≤ adm are sufficient conditions under the partial order relationship ⪯ LU for interval-valued optimal control problems. The results of this paper could help construct evolutionary algorithms to solve interval-valued optimal control problems. [ABSTRACT FROM AUTHOR]
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- 2024
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10. Identification and validation of GABA‐driven subtypes and prognosis signature of lung adenocarcinoma.
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Li, Lifeng, Sun, Shilong, Peng, Mengle, Wu, Kai, Duan, Xiaoran, Xue, Ruyue, Yang, Meijia, Zhang, Xu, and Zhao, Jie
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GENETIC databases , *MEDICAL sciences , *PROGNOSIS , *CYTOTOXIC T cells , *GENE expression - Abstract
Recent studies confirmed that the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) can regulate the proliferation and migration of tumour cells.[[1], [3]] Lung adenocarcinoma (LUAD) is the subtype with the largest proportion of lung cancer.[[5]] Huang et al. confirmed that GABA content in LUAD tissues was obviously higher than normal tissues by collecting clinical tissues.[7] By analysing GABA expression in different LUAD patients, we established a GABA-driven LUAD classification and developed a GABA-driven prognostic signature. (F) Nomogram for LUAD patients. gl In conclusion, based on the differential expression of GABA in LUAD patients, we classified LUAD patients and comprehensively considered the clinical significance of the classification. After difference analysis of these genes in tumour and normal tissue by "limma" package, 108 GABA core difference genes were obtained according to the absolute value of logFC > .5 (Table S1). Based on 108 GABA core differential genes, consensus clustering was performed in The Cancer Genome Atlas (TCGA)-LUAD queue ( I n i = 555) by using the "ConsensusClusterPlus" package. [Extracted from the article]
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- 2023
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11. Shear behavior of precast ultrahigh-performance concrete (UHPC) segmental beams with external tendons and dry joints.
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Ye, Meng, Li, Lifeng, Yoo, Doo-Yeol, Wang, Lianhua, Li, Huihui, and Shao, Xudong
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PRECAST concrete , *TENDONS , *SHEAR strength , *STRUT & tie models , *FAILURE mode & effects analysis , *DURABILITY - Abstract
In this study, ultrahigh-performance concrete (UHPC) was utilized in precast segmental beams to reduce the self-weight, shorten the construction time, and improve the performance and durability of bridges. Owing to the discontinuity in the joints, shear behavior plays a critical role in the overall structural performance of precast UHPC segmental beams (PUSBs). Therefore, four dry-jointed segmental specimens along with one monolithic specimen were designed and tested under a two-point concentrated load with various joint types, shear span-to-depth ratios (λ), and numbers of shear keys. Two types of shear failure modes were observed in the tests: shear compression failure of the web (λ = 1.44 and 2.56) and local shear failure of the flanges at the joint (λ = 3.67). The shear capacity, stiffness, and cracking load of the dry-jointed segmental specimens were lower than those of the monolithic specimen, and the single-keyed specimen exhibited better shear behavior than the three-keyed specimen. Increasing λ decreased the shear strength and stiffness of the segmental beams and considerably affected their failure modes and crack distributions. Additionally, four UHPC design codes were evaluated for their accuracy in estimating the shear strength of the specimens, and a simplified strut-and-tie model was developed to predict the shear strength of externally pre-stressed PUSBs. Finally, several design recommendations were proposed. This study is expected to facilitate the research and application of PUSBs. [ABSTRACT FROM AUTHOR]
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- 2023
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12. Management of Multiple Head and Neck Paragangliomas With Assistance of a 3-D Model.
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Li, Lifeng, Xu, Hongbo, Chen, Xiaohong, Yu, Zhenya, Zhou, Jing, Mydlarz, Wojciech K., and London Jr, Nyall R.
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PREOPERATIVE care , *THREE-dimensional imaging , *GENETIC mutation , *NURSING care plans , *OPERATIVE surgery , *INTRAOPERATIVE care , *HEAD & neck cancer , *HUMAN anatomical models , *DISEASES , *TREATMENT effectiveness , *GENOMICS , *DESCRIPTIVE statistics , *RESEARCH funding , *PARAGANGLIOMA , *COMPUTED tomography , *DISEASE management , *LONGITUDINAL method , *GLOMUS jugulare tumors - Abstract
Introduction: Extirpation of multiple head and neck paragangliomas carries challenge due to close anatomic relationships with critical neurovascular bundles. Objectives: This study aims to assess whether the application of 3-D models can assist with surgical planning and treatment of these paragangliomas, decrease surgically related morbidity and mortality. Methods: Fourteen patients undergoing surgical resection of multiple head and neck paragangliomas were enrolled in this study. A preoperative 3-D model was created based on radiologic data, and relevant critical anatomic relationships were preoperatively assessed and intraoperatively validated. Results: All 14 patients presented with multiple head and neck paragangliomas, including bilateral carotid body tumors (CBT, n = 9), concurrent CBT with glomus jugulare tumors (GJT, n = 4), and multiple vagal paragangliomas (n = 1). Ten patients underwent genomic analysis and all harbored succinate dehydrogenase complex subunit D (SDHD) mutations. Under guidance of the 3-D model, the internal carotid artery (ICA) was circumferentially encased by tumor on 5 of the operated sides, in 4 (80%) of which the tumor was successfully dissected out from the ICA, whereas ICA reconstruction was required on one side (20%). Following removal of CBT, anterior rerouting of the facial nerve was avoided in 3 (75%) of 4 patients during the extirpation of GJT with assistance of a 3-D model. Two patients developed permanent postoperative vocal cord paralysis. There was no vessel rupture or mortality in this study cohort. Conclusion: The 3-D model is beneficial for establishment of a preoperative strategy, as well as planning and guiding the intraoperative procedure for resection of multiple head and neck paragangliomas. [ABSTRACT FROM AUTHOR]
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- 2023
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13. Experimental and theoretical investigation of the shear lag effect in the novel non-prismatic prestressed CSW–UHPC composite box girders.
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Li, Huihui, Li, Lifeng, Yoo, Doo-Yeol, Ye, Meng, Zhou, Cong, and Shao, Xudong
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Due to their featured mechanical and structural merits, such as the light self-weight, excellent prestressing efficiency, appealing appearance, and optimal shear force and bending moment distributions in corrugated steel webs (CSWs) and concrete flanges, the prestressed concrete composite box girders with CSWs (CCBGCSWs) are popularly applied in highway bridges nowadays. To further enhance the cracking resistance of the concrete flanges of conventional prestressed CCBGCSWs, by replacing the regular concrete flanges with that made by ultra-high-performance concrete (UHPC) (i.e., with the much superior mechanical properties), this paper proposed a novel non-prismatic prestressed CSW–UHPC composite box girder to achieve the lighter dead weight, superior spanning capacity, and more rapid and cost-efficient construction for highway bridges. Owing to the differences in both the geometric dimensions and material properties, shear lag behavior of the proposed novel non-prismatic prestressed CSW–UHPC composite box girder could significantly differ from that of conventional prestressed CCBGCSWs. The shear lag effect refers to the non-uniform distributions of the longitudinal bending normal stress within the flanges caused by shear interaction between the webs and flanges, and the improper consideration of the shear lag behavior would impair the safety of thin-walled CCBGCSWs, especially the proposed novel non-prismatic prestressed CSW–UHPC composite box girder. Therefore, to investigate the shear lag behavior of the proposed novel non-prismatic prestressed CSW–UHPC composite box girder during different construction stages, a representative test specimen (5.55 m in length) with different boundary conditions (e.g., simply supported and cantilever) was designed and investigated under five different loading cases using the experimental tests and finite element (FE) analyses. In addition, a modified bar simulation method was proposed for the theoretical analysis of the shear lag behavior of the girder, and its feasibility and effectiveness were demonstrated through the comparisons to the experimental and numerical results. Finally, the results indicated that (i) the shear lag effect of UHPC flanges in the stress concentration region of the proposed novel non-prismatic CSW–UHPC composite box girder was more pronounced than that in the non-stress concentration region under different loading conditions; (ii) the shear lag coefficient (λ) of UHPC flanges in the non-stress and stress concentrated regions of the girder could be conservatively recommended not less than 1.1 and 1.25, respectively; and (iii) the boundary conditions and loading forms had significant influences on the shear lag behavior of the girder. The results of this study could serve as the experimental, numerical, and theoretical references for the shear lag behavior of the novel non-prismatic prestressed CSW–UHPC composite box girders. [ABSTRACT FROM AUTHOR]
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- 2023
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14. Norepinephrine inhibits CD8+ T-cell infiltration and function, inducing anti-PD-1 mAb resistance in lung adenocarcinoma.
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Geng, Qishun, Li, Lifeng, Shen, Zhibo, Zheng, Yuanyuan, Wang, Longhao, Xue, Ruyue, Xue, Wenhua, Peng, Mengle, and Zhao, Jie
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Background: Mental stress-induced neurotransmitters can affect the immune system in various ways. Therefore, a better understanding of the role of neurotransmitters in the tumour immune microenvironment is expected to promote the development of novel anti-tumour therapies. Methods: In this study, we analysed the plasma levels of neurotransmitters in anti-programmed cell death protein 1 (PD-1) monoclonal antibody (mAb)-resistance patients and sensitive patients, to identify significantly different neurotransmitters. Subsequently, animal experiments and experiments in vitro were used to reveal the specific mechanism of norepinephrine's (NE) effect on immunotherapy. Results: The plasma NE levels were higher in anti-PD-1 mAb-resistance patients, which may be the main cause of anti-PD-1 mAb resistance. Then, from the perspective of the immunosuppressive microenvironment to explore the specific mechanism of NE-induced anti-PD-1 mAb resistance, we found that NE can affect the secretion of C-X-C Motif Chemokine Ligand 9 (CXCL9) and adenosine (ADO) in tumour cells, thereby inhibiting chemotaxis and function of CD8+ T cells. Notably, the WNT7A/β-catenin signalling pathway plays a crucial role in this progression. Conclusion: NE can affect the secretion of CXCL9 and ADO in tumour cells, thereby inhibiting chemotaxis and the function of CD8+ T cells and inducing anti-PD-1 mAb resistance in lung adenocarcinoma (LUAD). [ABSTRACT FROM AUTHOR]
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- 2023
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15. Peri-operative complications following endoscopic-assisted transoral resection of parapharyngeal space tumors: retrospective analysis of 100 patients.
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Li, Lifeng, Gao, Yanyong, London Jr., Nyall R., Kou, Xiujuan, Wang, Weiwei, Xu, Hongbo, and Chen, Xiaohong
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VENOUS thrombosis , *CEREBROSPINAL fluid leak , *CEREBROSPINAL fluid , *BENIGN tumors , *PULMONARY embolism - Abstract
Purpose: A transoral surgical corridor can provide adequate exposure for extirpation of benign tumors arising from the parapharyngeal space (PPS). However, peri-operative complications following a transoral approach to the PPS have not been sufficiently described. This study retrospectively reviewed patients with PPS tumor extirpated via an endoscopic-assisted transoral approach, aiming to evaluate the safety of this approach and summarize the peri-operative complications.One hundred consecutive patients who underwent an endoscopic-assisted transoral resection of PPS benign tumors at a university hospital were enrolled. Indices including intraoperative catastrophic bleeding, cerebral spinal fluid (CSF) leak, post-operative respiratory airway swelling, cranial neural injury, operative field infection, oral suture dehiscence and venous thrombosis, were assessed from the date of surgery to 3 months after the surgery.Tumors in the PPS were safely and successfully removed via an endoscopic-assisted transoral approach for all 100 patients. Intra-operative CSF leak occurred in 3 patients, while the CSF leak was appropriately repaired intraoperatively without long-term post-operative CSF leak. No catastrophic bleeding, respiratory airway swelling, and operative field infection occurred. Cranial neuropathy occurred in 16 patients, five of whom fully recovered, while the remainder demonstrated permanent neural deficits. Oral suture dehiscence occurred in 13 patients, and all patients healed well after wound packing. Deep vein thrombosis was observed in three patients and pulmonary embolism in one patient, however, no severe consequences happened.An endoscopic-assisted transoral corridor is safe and effective for benign tumor extirpation in the PPS with few peri-operative complications.Methods: A transoral surgical corridor can provide adequate exposure for extirpation of benign tumors arising from the parapharyngeal space (PPS). However, peri-operative complications following a transoral approach to the PPS have not been sufficiently described. This study retrospectively reviewed patients with PPS tumor extirpated via an endoscopic-assisted transoral approach, aiming to evaluate the safety of this approach and summarize the peri-operative complications.One hundred consecutive patients who underwent an endoscopic-assisted transoral resection of PPS benign tumors at a university hospital were enrolled. Indices including intraoperative catastrophic bleeding, cerebral spinal fluid (CSF) leak, post-operative respiratory airway swelling, cranial neural injury, operative field infection, oral suture dehiscence and venous thrombosis, were assessed from the date of surgery to 3 months after the surgery.Tumors in the PPS were safely and successfully removed via an endoscopic-assisted transoral approach for all 100 patients. Intra-operative CSF leak occurred in 3 patients, while the CSF leak was appropriately repaired intraoperatively without long-term post-operative CSF leak. No catastrophic bleeding, respiratory airway swelling, and operative field infection occurred. Cranial neuropathy occurred in 16 patients, five of whom fully recovered, while the remainder demonstrated permanent neural deficits. Oral suture dehiscence occurred in 13 patients, and all patients healed well after wound packing. Deep vein thrombosis was observed in three patients and pulmonary embolism in one patient, however, no severe consequences happened.An endoscopic-assisted transoral corridor is safe and effective for benign tumor extirpation in the PPS with few peri-operative complications.Results: A transoral surgical corridor can provide adequate exposure for extirpation of benign tumors arising from the parapharyngeal space (PPS). However, peri-operative complications following a transoral approach to the PPS have not been sufficiently described. This study retrospectively reviewed patients with PPS tumor extirpated via an endoscopic-assisted transoral approach, aiming to evaluate the safety of this approach and summarize the peri-operative complications.One hundred consecutive patients who underwent an endoscopic-assisted transoral resection of PPS benign tumors at a university hospital were enrolled. Indices including intraoperative catastrophic bleeding, cerebral spinal fluid (CSF) leak, post-operative respiratory airway swelling, cranial neural injury, operative field infection, oral suture dehiscence and venous thrombosis, were assessed from the date of surgery to 3 months after the surgery.Tumors in the PPS were safely and successfully removed via an endoscopic-assisted transoral approach for all 100 patients. Intra-operative CSF leak occurred in 3 patients, while the CSF leak was appropriately repaired intraoperatively without long-term post-operative CSF leak. No catastrophic bleeding, respiratory airway swelling, and operative field infection occurred. Cranial neuropathy occurred in 16 patients, five of whom fully recovered, while the remainder demonstrated permanent neural deficits. Oral suture dehiscence occurred in 13 patients, and all patients healed well after wound packing. Deep vein thrombosis was observed in three patients and pulmonary embolism in one patient, however, no severe consequences happened.An endoscopic-assisted transoral corridor is safe and effective for benign tumor extirpation in the PPS with few peri-operative complications.Conclusion: A transoral surgical corridor can provide adequate exposure for extirpation of benign tumors arising from the parapharyngeal space (PPS). However, peri-operative complications following a transoral approach to the PPS have not been sufficiently described. This study retrospectively reviewed patients with PPS tumor extirpated via an endoscopic-assisted transoral approach, aiming to evaluate the safety of this approach and summarize the peri-operative complications.One hundred consecutive patients who underwent an endoscopic-assisted transoral resection of PPS benign tumors at a university hospital were enrolled. Indices including intraoperative catastrophic bleeding, cerebral spinal fluid (CSF) leak, post-operative respiratory airway swelling, cranial neural injury, operative field infection, oral suture dehiscence and venous thrombosis, were assessed from the date of surgery to 3 months after the surgery.Tumors in the PPS were safely and successfully removed via an endoscopic-assisted transoral approach for all 100 patients. Intra-operative CSF leak occurred in 3 patients, while the CSF leak was appropriately repaired intraoperatively without long-term post-operative CSF leak. No catastrophic bleeding, respiratory airway swelling, and operative field infection occurred. Cranial neuropathy occurred in 16 patients, five of whom fully recovered, while the remainder demonstrated permanent neural deficits. Oral suture dehiscence occurred in 13 patients, and all patients healed well after wound packing. Deep vein thrombosis was observed in three patients and pulmonary embolism in one patient, however, no severe consequences happened.An endoscopic-assisted transoral corridor is safe and effective for benign tumor extirpation in the PPS with few peri-operative complications. [ABSTRACT FROM AUTHOR]
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- 2024
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16. Experimental study on the structural performance of a novel composite bent cap with a partially precast UHPC-steel composite shell.
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Li, Lifeng, Tang, Jiahao, Ye, Meng, Jin, Weimeng, Xie, Kun, and Shao, Xudong
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INTERFACIAL bonding , *FLEXURAL strength , *MOMENTS method (Statistics) , *COMPOSITE columns , *CONCRETE , *CANTILEVERS - Abstract
This study proposed a novel composite bent cap (CBC) consisting of a precast ultra-high performance concrete (UHPC)-steel composite shell and an on-site poured concrete core to help reduce lifting weight and improve structural performance for the precast assembly of the large-cantilevered bent caps. The precast UHPC composite shell served as permanent formworks, providing protection, good durability, and reliable interfacial bonding capacity. The on-site poured concrete core enhanced the structural integrity, stiffness, and load-bearing capacity. Techno-economic analysis showed that the CBC is a competitive scheme for modern urban viaducts owing to the less formwork work, lighter lifting weight, and satisfactory construction efficiency. The flexural and shear behavior of the CBCs were studied through a single-point cantilever loading test with a large-scaled (1:2.5) specimen. Experimental results were obtained including deflection, strain, crack distribution, cracking load, and ultimate load. The results showed that the CBCs exhibited sufficient load-bearing capacity and considerable deformability, and the flexural strength dominated the design. No interfacial separation or failure was observed between the concrete core and the UHPC-steel composite shell. Moreover, predicting methods of the cracking moment, flexural capacity, and shear capacity were explored and discussed. Finally, considerations for designing and constructing the novel CBCs were proposed. [ABSTRACT FROM AUTHOR]
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- 2024
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17. Resection of Carotid Body Tumors in Patients of Advanced Age: Experience From a Single Center.
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Li, Lifeng, Xu, Hongbo, Zhou, Jing, Mydlarz, Wojciech K., Yu, Zhengya, Chen, Xiaohong, and London, Nyall R.
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LENGTH of stay in hospitals , *CAROTID artery diseases , *CAROTID body , *HEAD & neck cancer , *SURGICAL complications , *DEGLUTITION disorders , *VASCULAR surgery , *DESCRIPTIVE statistics , *OLD age , *MIDDLE age - Abstract
Introduction: Resection of carotid body tumor (CBT) in patients of advanced ages has not been appreciated. Objectives: This study aims to assess the clinical characteristics and perioperative comorbidities for CBT resection in patients of advanced age and to validate the application of an "isolated island" technique for extirpation of CBT. Methods: Eight patients of advanced age (≥60 years) who underwent CBT resection were enrolled as the study group (SG). Another 29 patients of younger age (<45 years old) underwent CBT extirpation were assigned as the control group (CG). The perioperative issues were compared between these 2 groups. Results: The "isolated island" technique was successfully applied for resection of CBT in all 37 patients. The prevalence of Shamblin classification I, II, and III tumors in the SG was 12.5%, 62.5%, and 25%; whereas in the CG was 10.3%, 55.2%, and 34.5%, respectively. Bilateral CBT was observed in 7 patients of the CG and none in the SG. Vascular reconstruction was required for 1 (12.5%) patient in the SG, while it was required for 8 (27.6%) patients in the CG. Postoperative vocal cord palsy occurred in 37.5% of patients in SG, whereas the vocal cord palsy (34.5%) and dysphagia (6.9%) were commonly encountered in CG. In addition to postoperative length of stay (P =.004), no significant difference for operative time, intraoperative blood loss, or mortality were observed between these 2 groups (P >.05). Conclusion: Extirpation of CBT in patients of advanced age is rationale in appropriately selected patients. The "isolated island" technique is safe for CBT resection with seemingly low complication rates. [ABSTRACT FROM AUTHOR]
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- 2023
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18. Molecular beacon based real-time PCR p1 gene genotyping, macrolide resistance mutation detection and clinical characteristics analysis of Mycoplasma pneumoniae infections in children.
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Li, Lifeng, Ma, Jiayue, Guo, Pengbo, Song, Xiaorui, Li, Mingchao, Yu, Zengyuan, Yu, Zhidan, Cheng, Ping, Sun, Huiqing, and Zhang, Wancun
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MYCOPLASMA pneumoniae infections , *MYCOPLASMA pneumoniae , *GENETIC mutation , *POLYMERASE chain reaction , *GENES , *DETECTION limit - Abstract
Background: Mycoplasma pneumoniae can be divided into different subtypes on the basis of the sequence differences of adhesive protein P1, but the relationship between different subtypes, macrolide resistance and clinical manifestations are still unclear. In the present study, we established a molecular beacon based real-time polymerase chain reaction (real-time PCR) p1 gene genotyping method, analyzed the macrolide resistance gene mutations and the relationship of clinical characteristics with the genotypes.Methods: A molecular beacon based real-time PCR p1 gene genotyping method was established, the mutation sites of macrolide resistance genes were analyzed by PCR and sequenced, and the relationship of clinical characteristics with the genotypes was analyzed.Results: The detection limit was 1-100 copies/reaction. No cross-reactivity was observed in the two subtypes. In total, samples from 100 patients with positive M. pneumoniae detection results in 2019 and 2021 were genotyped using the beacon based real-time PCR method and P1-1 M. pneumoniae accounted for 69.0%. All the patients had the A2063G mutation in the macrolide resistance related 23S rRNA gene. Novel mutations were also found, which were C2622T, C2150A, C2202G and C2443A mutations. The relationship between p1 gene genotyping and the clinical characteristics were not statistically related.Conclusion: A rapid and easy clinical application molecular beacon based real-time PCR genotyping method targeting the p1 gene was established. A shift from type 1 to type 2 was found and 100.0% macrolide resistance was detected. Our study provided an efficient method for genotyping M. pneumoniae, valuable epidemiological monitoring information and clinical treatment guidance to control high macrolide resistance. [ABSTRACT FROM AUTHOR]- Published
- 2022
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19. An Endoscopic Endonasal Nasopharyngectomy with Posterolateral Extension.
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Li, Lifeng, London Jr., Nyall R., Prevedello, Daniel M., and Carrau, Ricardo L.
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PTERYGOID muscles , *CAROTID artery , *ENDOSCOPIC surgery , *EUSTACHIAN tube , *TORUS , *NASOPHARYNX - Abstract
Background Invasion depth influences the choice for extirpation of nasopharyngeal malignancies. This study aims to validate the feasibility of endoscopic endonasal resection of lesions with a posterolateral invasion. As a secondary goal, the study intends to propose a classification system of endoscopic endonasal nasopharyngectomy determined by the depth of posterolateral invasion. Methods Eight cadaveric specimens (16 sides) underwent progressive nasopharyngectomy using an endoscopic endonasal approach. Resection of the torus tubarius, Eustachian tube (ET), medial pterygoid plate and muscle, lateral nasal wall, and lateral pterygoid plate and muscle were sequentially performed to expose the fossa of Rosenmüller, petroclival region, parapharyngeal space (PPS), and jugular foramen, respectively. Results Technical feasibility of endonasal nasopharyngectomy toward a posterolateral direction was validated in all 16 sides. Nasopharyngectomy was classified into four types as follows: (1) type 1: resection restricted to the posterior or superior nasopharynx; (2) type 2: resection includes the torus tubarius which is suitable for lesions extended into the petroclival region; (3) type 3: resection includes the distal cartilaginous ET, medial pterygoid plate, and muscle, often required for lesions extending laterally into the PPS; And (4) type 4: resection includes the lateral nasal wall, pterygoid plates and muscles, and all the cartilaginous ET. This extensive resection is required for lesions involving the carotid artery or extending to the jugular foramen region. Conclusion Selected lesions with posterolateral invasion into the PPS or jugular foramen is amenable to a resection via expanded endonasal approach. Classification of nasopharyngectomy based on tumor depth of posterolateral invasion helps to plan a surgical approach. [ABSTRACT FROM AUTHOR]
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- 2022
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20. Anatomical Variants of Post-ganglionic Fibers within the Pterygopalatine Fossa: Implications for Endonasal Skull Base Surgery.
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Li, Lifeng, London Jr., Nyall R., Prevedello, Daniel M., and Carrau, Ricardo L.
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SKULL surgery , *MAXILLARY nerve , *LACRIMAL apparatus , *PTERYGOPALATINE ganglion , *SKULL base , *NASAL cavity , *INNERVATION - Abstract
Objectives The vidian nerve provides parasympathetic innervation to the nasal cavity and the lacrimal gland. Previous anatomic studies have primarily focused on preservation or severance of the vidian nerve proximal to the pterygopalatine ganglion (PPG). This study aimed to assess its neural fibers within the pterygopalatine fossa after synapsing at the PPG, and to explore potential clinical implications for endoscopic endonasal skull base surgery. Methods An endonasal transpterygoid approach was performed on eight cadaveric specimens (16 sides). The PPG and maxillary nerve within the pterygopalatine fossa were divided. The vidian nerve was traced retrograde into the foramen lacerum, and postganglionic fibers distal to the PPG were dissected following the zygomatic nerve into the orbit. Potential communicating branches between the ophthalmic nerve (V1) and the PPG were also explored. Results All sides showed a plexus of neural communications between the PPG and the maxillary nerve. The zygomatic nerve exits the maxillary nerve close to the foramen rotundum, piercing the orbitalis muscle to enter the orbit in all sides. The zygomatic nerve was identified running beneath the inferior rectus muscle toward a lateral direction. In 7/16 sides (43.75%), a connecting branch between V 1 and the pterygopalatine ganglion was observed. Conclusion Neural communications between the PPG and the maxillary nerve were present in all specimens. A neural branch from V 1 to the PPG potentially contributes additional postganglionic parasympathetic function to the lacrimal gland. [ABSTRACT FROM AUTHOR]
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- 2022
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21. Critical review of the criterion of polysaccharide purity.
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Zhang, Xueting, Li, Lifeng, Fung, Hauyee, Chen, Niping, Shan, Pengfei, Zhou, Yifa, and Han, Quanbin
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MOLECULAR size , *POLYMER blends , *FOOD additives , *POLYSACCHARIDES , *CHEMICAL structure - Abstract
Natural polysaccharides attract scientists and industries' interest with diverse applications in biomaterials, immune regulation, gut microbiota regulation, food additives, and more. Nevertheless, the absence of standardized purity criteria created significant challenges in characterizing polysaccharides, leading to varied and complicated structures, and impeding progress in research and development. Consequently, it is essential to obtain samples that adhere to high-level and unified purity standards for effective polysaccharide research. Herein we review current methods for assessing polysaccharide purity, emphasizing a commonly neglected impurity: mixtures of polysaccharides with similar molecular sizes. Such a mixture, previously regarded as a single sample, can present a much more complex and ambiguous chemical structure. To address this challenge, we propose enhancing the purity criteria to identify these mixtures. Briefly, the molecular size changes are monitored following hydrolysis with diagnostic enzymes which are identified through methylation and monosaccharide analysis. A pure polymer will exhibit a complete shift in its HPGPC peak, while a polymer mixture will display residual peaks. Establishing standardized criteria for assessing polysaccharide quality represents a significant milestone in the industrialization of these important biomolecules. By enabling accurate, consistent, reliable characterization, this advancement lays the groundwork for broader polysaccharide applications in pharmaceuticals, food, materials, and beyond. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2025
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22. Interpretable ensemble machine learning models for predicting the shear capacity of UHPC joints.
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Ye, Meng, Li, Lifeng, Jin, Weimeng, Tang, Jiahao, Yoo, Doo-Yeol, and Zhou, Cong
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FEATURE selection , *HIGH strength concrete , *DATABASES , *CIVIL engineering , *STRUCTURAL reliability - Abstract
Precast ultra-high-performance concrete (UHPC) structures (PUSs) have gained increasing research and application interest in civil engineering owing to the combination of advanced construction materials and methods. UHPC joints are critical parts of PUSs; thus, an accurate prediction of their shear capacity (SC) is essential to ensure structural safety and reliability. However, existing equations for predicting SC have limited accuracy and applicability owing to their simplified assumptions and restricted input parameters. To address these challenges, this study used machine learning (ML) approaches to develop a unified and accurate predictive model for various types of UHPC joints. A well-curated database containing 218 UHPC joints with diverse types and configurations was established. Six ensemble algorithms and four traditional algorithms were employed to develop predictive models, and eight existing equations were compared for performance evaluation. Both correlation-based and SHAP-based feature selection methods were used to optimize the model accuracy. The ensemble algorithms demonstrated better performance than the traditional individual algorithms, with the gradient boosting machine (GBM) model ranked as the best ML model for SC. The ML model outperformed existing equations in all evaluated metrics, demonstrating its accuracy and robustness. Furthermore, Shapley Additive exPlanations (SHAP) analysis was employed to interpret the ML model, thereby providing insights into influential features and their relationships. These findings demonstrate the advantages of ML methods in predicting the SC of UHPC joints and provide valuable guidance for the structural design and research on PUSs. • An updated database consisting of 218 push-off tests of various types of UHPC joints is established. • Ensemble and individual ML models are developed to predict the shear capacity of UHPC joints. • Correlation-based and SHAP-based feature selection methods are used to optimize the ML models. • The best ML model is compared with the existing equations to highlight the advantages of the ML method. • The ML models are globally and individually interpreted using the SHAP analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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23. Synthesis, Crystal Structure and Fluorescent Property of a Novel Cd(II) Coordination Polymer based on Nitrogen-Containing Ligands.
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Li, Lifeng, Gu, Xiong, Yang, Chongfu, Liu, Na, Ye, Yanqing, and Ma, Yulu
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COORDINATION polymers , *CRYSTALLINE polymers , *HYDROGEN bonding interactions , *LIGANDS (Chemistry) , *SPACE groups - Abstract
A novel Cadmium(II) coordination polymer, namely {[Cd(L)(bpmh)0.5(DMA)(H2O)]}n (CP 1), has been successfully synthesized under solvothermal conditions using H2L (5-(1-oxoisoindion-2-yl)isophthalic acid) and bpmh ((1
E ,2E )-1,2-bis(pyridine-4-ylmethylene)hydrazine) ligand. The CP 1 is well described by single-crystal X-ray diffraction, PXRD, FT-IR, TGA and solid-state fluorescence properties. X-ray single crystal diffraction analysis shows that CP 1 crystallizes in theP-1 space group, and possesses 1D ladder chains, which were further connected by hydrogen bonding interactions to form 3D supramolecular architecture. Results of the property studies showed that we successfully synthesized a pure phase fluorescent material with good thermal stability and has potential applications for the development of future fluorescent materials.(II)Single-crystal X-ray analysis shows that a novel Cd (II) fluorescence coordination polymer based on nitrogen-containing aromatic ligands was described in this work.Graphical Abstract: A novel Cadmium(II) coordination polymer, namely {[Cd(L)(bpmh)0.5(DMA)(H2O)]}n (CP 1), has been successfully synthesized under solvothermal conditions using H2L (5-(1-oxoisoindion-2-yl)isophthalic acid) and bpmh ((1E ,2E )-1,2-bis(pyridine-4-ylmethylene)hydrazine) ligand. The CP 1 is well described by single-crystal X-ray diffraction, PXRD, FT-IR, TGA and solid-state fluorescence properties. X-ray single crystal diffraction analysis shows that CP 1 crystallizes in theP-1 space group, and possesses 1D ladder chains, which were further connected by hydrogen bonding interactions to form 3D supramolecular architecture. Results of the property studies showed that we successfully synthesized a pure phase fluorescent material with good thermal stability and has potential applications for the development of future fluorescent materials.(II)Single-crystal X-ray analysis shows that a novel Cd (II) fluorescence coordination polymer based on nitrogen-containing aromatic ligands was described in this work. [ABSTRACT FROM AUTHOR]- Published
- 2024
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24. Exploring factors affecting the dissociation energies of C–O and C–C bonds in lignin oligomers.
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Li, Lifeng, Ouyang, Xinping, and Qian, Yong
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LIGNIN structure , *LIGNINS , *RANDOM forest algorithms , *OLIGOMERS , *POLAR solvents , *DENSITY functional theory , *DEPOLYMERIZATION - Abstract
[Display omitted] • Key factors for lignin dissociation are investigated by DFT and machine learning. • Oxidating C α -OH to C α = O in lignin benefits the cleavage of β-O-4 and β-1 bonds. • Hydroxyl and methoxy benefit the cleavage of C β -1 and C α -C β bonds in β-1 dimer. • Chlorine atoms substituting in the benzene ring favor the cleavage of β-O-4 bond. • n-Hexane favors the cleavage of C α -C β bond while water has the opposite effect. The bond dissociation energy (BDE) of lignin is a key factor for lignin depolymerization, assisting in revealing the depolymerization mechanism. However, the impact of substituent as well as solvent, which usually stay together, on BDE of lignin remains unclear. Here, density functional theory (DFT) calculation is employed to compute the BDE of C–O and C–C bonds in lignin oligomers with six substituents in four solvents. The relationship models between multiple factors and BDE are established using random forest algorithm, achieving a predictive accuracy of 0.97. The results show that oxidating hydroxyl to ketone benefits the cleavage of β-O-4 and β-1 bonds. Hydroxyl and methoxy effectively contribute to breaking the C β -1 and C α –C β bonds in the β-1 dimer. Polar solvents combined with hydroxyl promote C–O bond dissociation, while alkyl-containing solvents favor C–C bond dissociation. These findings provide valuable insights into lignin depolymerization, pre-depolymerization structural modifications, and the prediction of depolymerization pathways. [ABSTRACT FROM AUTHOR]
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- 2024
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25. Dance Fitness Action Recognition Method Based on Contour Image Spatial Frequency Domain Features and Few-Shot Learning.
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Chi, Qinglong and Li, Lifeng
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IMAGE recognition (Computer vision) , *ARTIFICIAL intelligence , *NATURAL language processing , *FEATURE extraction - Abstract
In recent years, the research work of artificial intelligence technology has progressed rapidly, and various classic Few-Shot learning models have achieved unprecedented success in many artificial intelligence application fields. These include face recognition, object classification detection and tracking, speech recognition, and natural language processing, which greatly facilitate our lives. This paper aims to identify dance fitness movements based on contour image spatial frequency domain features and Few-Shot learning technology. This paper proposes a Few-Shot learning method based on contrastive average loss for Few-Shot learning. This method makes the learned model more representative by improving the loss function and performing a normalization process, and it proposes a feature extraction algorithm that combines improved LBP and HOG for action recognition technology. The experimental results show that the recognition accuracy of the algorithm in this paper is 93.10%, 90.30%, and 92.70% for walking, opening hands, and running, respectively. This illustrates the effectiveness of the fusion feature algorithm. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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26. Anatomical Variations of the Jugular Foramen Region in Patients with Pulsatile Tinnitus.
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Li, Lifeng, Yang, Bentao, Ma, Xiaobo, Li, Pingdong, Creighton, Francis X., Carrau, Ricardo L., and London Jr., Nyall R.
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ANATOMICAL variation , *INTERNAL carotid artery , *CEREBELLOPONTILE angle , *CRANIAL sinuses , *SEMICIRCULAR canals - Abstract
Objective Structural anomalies of the jugular foramen (JF) and adjacent structures may contribute to development of pulsatile tinnitus (PT). The goal of this study was to assess anatomical variants in the ipsilateral JF region in patients with PT and to explore possible predisposing factors for PT. Methods One hundred ninety-five patients with PT who underwent CT angiography and venography of the temporal bone were retrospectively analyzed. Anatomic variants including dominance of the ipsilateral JF, bony deficiency of the sigmoid sinus and internal carotid artery canal, high riding or dehiscent jugular bulb, dehiscence of the superior semicircular canal, tumors in the JF region, or cerebellopontine angle were assessed. Results Of 195 patients with PT, the prevalence of a dominant JF on the ipsilateral side of patients with PT was 67.2%. Furthermore, the dominant JF demonstrated a significant correlation with the presence of ipsilateral PT (p < 0.001). No anatomical variants were present in 22 patients (11.3%), whereas in patients with structural variants, bony deficiency of the sigmoid sinus was most common (65.6%), followed by high riding (54.9%) or dehiscent jugular bulb (14.4%). Dehiscent internal carotid artery canal (3.1%) and superior semicircular canal (4.1%) were occasionally identified, while arteriovenous fistula, arterial aneurysm and tumors arising from the JF region or cerebellopontine angle were rarely encountered. Conclusion Structural abnormalities of the JF and adjacent structures may predispose to the development of PT. Knowledge of these anatomical variants in the JF region may help establish a clinical strategy for addressing PT. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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27. Time-dependent Seismic Fragility Assessment for Aging Highway Bridges Subject to Non-uniform Chloride-induced Corrosion.
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Li, Huihui, Li, Lifeng, Zhou, Guojie, and Xu, Liang
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BRIDGE foundations & piers , *CONCRETE beams , *REINFORCED concrete , *ROADS , *CURVATURE - Abstract
This paper proposes an alternative time-dependent seismic fragility assessment framework considering the variable correlation of structural random parameters for aging highway bridges subject to non-uniform chloride-induced corrosion attacks. The proposed systematic framework is implemented to perform a probabilistic time-dependent seismic fragility assessment for a typical multi-span reinforced concrete continuous girder (MSRCCG) bridge. Effects of non-uniform chloride-induced deterioration on the time-evolving seismic capacity, seismic demand of reinforced concrete (RC) columns, and the time-dependent seismic fragility of the case-study bridge are investigated using nonlinear sectional moment-curvature and nonlinear time history analysis. Furthermore, this paper performs comparative studies to investigate the influence of variable correlation of structural random parameters on the time-variant seismic capacity, seismic demand of RC columns, and time-dependent seismic fragility of the case-study bridge. The results indicate the following conclusions: (1) Non-uniform chloride-induced corrosion may change the vulnerable position and the damage mechanisms of RC columns; (2) Due to non-uniform chloride-induced deterioration, the flexural capacity and curvature ductility of RC columns may exhibit a nonlinear reduction, while there is a nonlinear accelerated growth of time-dependent seismic fragility for aging highway bridges along their service lives; (3) The time-variant seismic capacity (i.e., the flexural capacity and curvature ductility) and seismic demand of RC columns tends to have a certain reduction and increase by ignoring the variable correlation of structural random parameters, respectively; and (4) The time-dependent seismic vulnerabilities of aging highway bridges may be overestimated by ignoring the variable correlation of structural random parameters. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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28. Optical alignment and radiative flux characterization of a multi-source high-flux solar simulator.
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Pottas, Johannes, Li, Lifeng, Habib, Mustafa, Wang, Chi-Hwa, Coventry, Joe, and Lipiński, Wojciech
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DIGITAL photogrammetry , *NEUTRAL density filters , *FOCAL planes , *DIGITAL cameras , *SOLAR temperature , *RADIATION sources - Abstract
High-flux solar simulators are research-grade sources of artificial radiation mimicking optical characteristics of concentrating solar systems. They allow for experimental evaluation of high-temperature solar thermal devices and materials under controlled and reproducible conditions. In this study, we demonstrate the application of close-range photogrammetry in tandem with radiometry to optically align radiation modules of a multi-source high-flux solar simulator and to characterize its radiative output. The photogrammetric setup consists of photogrammetry targets, a digital camera and photogrammetry software. The radiometric measurements are conducted using mobile Lambertian targets, a heat flux gauge, and a complementary metal-oxide semi-conductor camera equipped with neutral density filters. An iterative procedure for adjusting lamp positions allows obtaining optical configurations of radiative modules meeting experimental requirements of high and ultra-high temperature solar thermal and thermochemical research. Close-range photogrammetry is demonstrated to be a convenient and effective method to obtain the as-built geometric configuration of the solar simulator setup. We report characteristics of an example radiative module configuration for a subset of six radiation modules. The peak and mean radiative fluxes over a 60-mm diameter flat target located in the focal plane are 3080 kW m−2 and 1135 kW m−2, respectively. The mean aiming error, defined as the average distance between theoretical and actual aiming points in the focal plane, is reduced from 37.20 mm to 4.50 mm for the pre- and post-alignment configurations, respectively. • Optical alignment and radiative flux characterization of a high-flux solar simulator are presented. • A combined methodology of close-range photogrammetry and radiometry is applied. • Close-range photogrammetry allows capturing the geometric configuration of the entire HFSS setup. • The mean aiming error is reduced from 37.20 mm to 4.50 mm after photogrammetry alignment. • A mean radiative flux of 1135 kW m-2 is obtained over a 60-mm dia. flat target using six lamps. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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29. Comparative Genomic Analysis of Streptococcus pneumoniae Strains: Penicillin Non-susceptible Multi-drug-Resistant Serotype 19A Isolates.
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Li, Lifeng, Zhou, Juanjuan, Li, Mingchao, Yu, Zengyuan, Gao, Kaijie, Yang, Junwen, Cheng, Ping, Yang, Junmei, Zhang, Wancun, Yu, Zhidan, and Sun, Huiqing
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STREPTOCOCCUS pneumoniae , *GENOMICS , *MULTIDRUG resistance , *DRUG resistance in bacteria , *PNEUMOCOCCAL vaccines , *DRUG resistance , *MENINGITIS , *PNEUMOCOCCAL pneumonia - Abstract
Streptococcus pneumoniae can cause several diseases including otitis media, sinusitis, pneumonia, sepsis and meningitis. The introduction of pneumococcal vaccines has changed the molecular epidemiological and antibiotic resistance profiles of related diseases. Analysis of molecular patterns and genome sequences of clinical strains may facilitate the identification of novel drug resistance mechanism. Three multidrug resistance 19A isolates were verified, serotyped and the complete genomes were sequenced combining the Pacific Biosciences and the Illumina Miseq platform. Genomic annotation revealed that similar central networks were found in the clinical isolates, and Mauve alignments indicated high similarity between different strains. The pan-genome analysis showed the shared and unique cluster in the strains. Mobile elements were predicted in the isolates including prophages and CRISPER systems, which may participate in the virulence and antibiotic resistance of the strains. The presence of 31 virulence factor genes was predicted from other pathogens for PRSP 19339 and 19343, while 30 for PRSP 19087. Meanwhile, 33 genes antibiotic resistance genes were predicted including antibiotic resistance genes, antibiotic-target genes and antibiotic biosynthesis genes. Further analysis of the antibiotic resistance genes revealed new mutations in the isolates. By comparative genomic analysis, we contributed to the understanding of resistance mechanism of the clinical isolates with other serotype strains, which could facilitate the concrete drug resistance mechanism study. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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30. Aerodynamics Analysis of the Impact of Nasal Surgery on Patients with Obstructive Sleep Apnea and Nasal Obstruction.
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Li, Lifeng, Han, Demin, Zang, Hongrui, and London, Nyall R.
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NASAL surgery , *SLEEP apnea syndromes , *COMPUTATIONAL fluid dynamics , *AERODYNAMICS , *AIRWAY resistance (Respiration) , *AIR flow - Abstract
Objective: The purpose of this study was to evaluate the effects of nasal surgery on airflow characteristics in patients with obstructive sleep apnea (OSA) by comparing the alterations of airflow characteristics within the nasal and palatopharyngeal cavities. Methods: Thirty patients with OSA and nasal obstruction who underwent nasal surgery were enrolled. A pre- and postoperative 3-dimensional model was constructed, and alterations of airflow characteristics were assessed using the method of computational fluid dynamics. The other subjective and objective clinical indices were also assessed. Results: By comparison with the preoperative value, all postoperative subjective symptoms statistically improved (p < 0.05), while the Apnea-Hypopnea Index (AHI) changed little (p = 0.492); the postoperative airflow velocity and pressure in both nasal and palatopharyngeal cavities, nasal and palatopharyngeal pressure differences, and total upper airway resistance statistically decreased (all p < 0.01). A significant difference was derived for correlation between the alteration of simulation metrics with subjective improvements (p < 0.05), except with the AHI (p > 0.05). Conclusion: Nasal surgery can decrease the total resistance of the upper airway and increase the nasal airflow volume and subjective sleep quality in patients with OSA and nasal obstruction. The altered airflow characteristics might contribute to the postoperative reduction of pharyngeal collapse in a subset of OSA patients. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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31. Anatomical Variations and Relationships of the Infratemporal Fossa: Foundation of a Novel Endonasal Approach to the Foramen Ovale.
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Li, Lifeng, London Jr., Nyall R., Prevedello, Daniel M., and Carrau, Ricardo L.
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ANATOMICAL variation , *MAXILLARY artery , *PTERYGOID muscles , *HEMORRHAGE , *TRISMUS - Abstract
Objective Access to the infratemporal fossa (ITF) is complicated by its complex neurovascular relationships. In addition, copious bleeding from the pterygoid plexus adds to surgical challenge. This study aims to detail the anatomical relationships among the internal maxillary artery (IMA), pterygoid plexus, V 3, and pterygoid muscles in ITF. Furthermore, it introduces a novel approach that displaces the lateral pterygoid plate (LPP) to access the foramen ovale. Design and Main Outcome Measures Six cadaveric specimens (12 sides) were dissected using an endonasal approach to the ITF modified by releasing and displacing the LPP and lateral pterygoid muscle (LPTM) as a unit. Subperiosteal elevation of the superior head of LPTM revealed the foramen ovale. The anatomic relationships among the V 3 , pterygoid muscles, pterygoid plexus, and IMA were surveyed. Results In 9/12 sides (75%), the proximal IMA ran between the temporalis and the LPTM, whereas in 3/12 sides (25%), the IMA pierced the LPTM. The deep temporal nerve was a consistent landmark to separate the superior and inferior heads of LPTM. An endonasal approach displacing the LPP in combination with a subperiosteal elevation of the superior head of LPTM provided access to the posterior trunk of V 3 and foramen ovale while sparing injury of the LPTM and exposing the pterygoid plexus. The anterior trunk of V 3 traveled anterolaterally along the greater wing of sphenoid in all specimens. Conclusion Displacement of the LPP and LPTM provided direct exposure of foramen ovale and V 3 avoiding dissection of the muscle and pterygoid plexus; thus, this maneuver may prevent intraoperative bleeding and postoperative trismus. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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32. Endoscopic Transoral Approach for Resection of Basal Cell Adenoma Arising in Parapharyngeal Space.
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Li, Lifeng, London Jr, Nyall R., Li, Shuling, Chen, Xiaohong, and Carrau, Ricardo L.
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ADENOMA , *SYMPTOMS , *INTERNAL carotid artery , *HISTOPATHOLOGY , *SALIVARY glands - Abstract
Objectives The clinical and radiological characteristics of the basal cell adenoma (BCA) and its association with the internal carotid artery (ICA) in the parapharyngeal space (PPS), have not been sufficiently explored. This study aims to analyze the characteristics of patients with BCA arising in the PPS and to evaluate the feasibility of a total resection via an endoscopic transoral corridor. Design and Main Outcome Measures The clinical, radiological, and histopathological characteristics of four patients with BCA arising in the PPS were retrospectively analyzed. The endoscopic transoral approach was performed for resection of BCA. Its technical nuances, perioperative comorbidities, and outcomes are introduced. Results The clinical presentation, symptoms, and signs of patients with BCA are variable. The tumor was lateral to the ICA in two patients and anterior to the ICA in the remaining two. All four BCA were successfully removed en bloc (n = 3) or by piecemeal (n = 1) via an endoscopic transoral approach. The ICA was not injured, and no additional nerve damage, venous bleeding, postoperative infection, or salivary gland fistula were encountered in any of the four patients. Cystic degeneration is the predominant appearance of BCA on MRI; however, they are difficult to differentiate from other lesions arising in the PPS. No recurrence was detected at the time of the study analysis. Conclusion BCA of the PPS could have variable relationships with the ICA. An endoscopic transoral approach can provide an adequate corridor for total resection of BCA in PPS with seemingly low morbidity. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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33. Impact Assessment of Flammable Gas Dispersion and Fire Hazards from LNG Tank Leak.
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Li, Lifeng, Luo, Jinheng, Wu, Gang, Li, Xinhong, Ji, Nan, and Zhu, Lixia
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FLAMMABLE gases , *COMPUTATIONAL fluid dynamics , *HEAT radiation & absorption , *DISPERSION (Chemistry) , *FLAME spread , *PHASE transitions - Abstract
This study conducts an impact assessment of flammable gas dispersion and fire hazards from LNG tank leak. The release source model is used to estimate LNG release rate. A CFD (computational fluid dynamics) based 3D model is established to simulate dispersion behavior of flammable gas from the phase transformation of LNG. Subsequently, a FDS (fire dynamics) based model is built to simulate the pool fire due to LNG tank leak. The impact of gas dispersion and fire on personnel and assets is assessed based on simulation results, which can provide a theoretical basis and method support for major accident assessment of tank leakage in large LNG receiving station. The results show that the dispersion of flammable gas from LNG tank leak has an obvious stage characteristic. The flammable gas reached a steady state around 300 s, and the corresponding coverage area is about 16250 m2. The pool fire simulations indicate that the steady flame is formed at 20 s. The flames flow along the wind, and the maximum temperature of the fire reaches 670°C, and the maximum thermal radiation reaches 624 kW/m2. According to the fire damage criteria, the pool fire from LNG tank leak may pose a serious threat on the safety of adjacent assets and personnel. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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- View/download PDF
34. Internal mechanism of perfect-reflector-backed dielectric gratings to achieve high diffraction efficiency.
- Author
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Li, Lifeng
- Subjects
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DIELECTRICS , *DIFFRACTION gratings , *SPECTRUM analysis instruments , *DIFFRACTIVE optical elements , *SPECTRUM analysis - Abstract
The work started 20 years ago [Appl. Opt. 42, 6255 (2003)] investigating the physical mechanism of multilayer dielectric reflection gratings to achieve 100% diffraction efficiency is extended to offer much deeper insight than before. How different diffraction amplitudes of the top surface corrugation contribute to the −1st-order efficiency of such a grating is shown analytically using a minimum set of real parameters. The two diffraction amplitudes transmitted through the corrugation play a dominant role in enabling DE = 100%. The necessary and sufficient condition for 100% efficiency is derived, and a very simple sufficient condition is also given. Moreover, the role of the reflection phase of the perfect-reflector, including the contribution due to optical path between the corrugation and the reflector, is emphasized. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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35. Impact of Varying Types of Nasal Septal Deviation on Nasal Airflow Pattern and Warming Function: A Computational Fluid Dynamics Analysis.
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Li, Lifeng, Zang, Hongrui, Han, Demin, and London Jr, Nyall R.
- Subjects
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AERODYNAMICS , *BODY temperature , *AIRWAY (Anatomy) , *RESPIRATORY measurements , *PARANASAL sinuses , *NASAL septum , *NOSE , *RESPIRATORY obstructions , *NASAL cavity , *RESPIRATION , *COMPUTED tomography - Abstract
Nasal septal deviations (NSD) have been categorized into 7 types. The effect of these different deviations on airflow pattern and warming function has not been fully investigated. The purpose of this study was to utilize a computational fluid dynamics approach to assess the impact of NSD of varying types on nasal airflow and warming function. Patients with each type of NSD were enrolled in the study, and a normal participant as the control. Using a computational fluid dynamics approach, modeling of nasal function was performed. Indices of nasal function including airflow redistribution, total nasal resistance, airflow velocity, and airflow temperature were determined. Among all types of NSD, the maximal velocity and total nasal resistance were markedly higher in type 4 and 7 deviations. The flow partition and velocity distribution were also altered in type 4 and 7 as well as type 2 and 6 deviations. Airflow in all categories of NSD was fully warmed to a similar degree. From a computational aerodynamics perspective, the type of septal deviation may contribute to altered airflow characteristics. However, warming function was similar between septal deviation types. Future studies will help to ascertain the functional importance of septal deviation types and the applicability of these computational studies. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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36. Effect of continuous esketamine infusion on brain white matter microstructure in patients with major depression: A diffusion tensor imaging study.
- Author
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Liu, Xiang, Wei, Zhipeng, Li, Lifeng, Li, Jiangping, Deng, Yingke, Liu, Yumeng, Li, Haijun, Peng, Dechang, Wan, Xin, and Wu, Guojiang
- Subjects
- *
DIFFUSION tensor imaging , *MENTAL depression , *WHITE matter (Nerve tissue) , *SUICIDAL ideation , *STATISTICAL power analysis - Abstract
Esketamine has demonstrated acute antidepressant effects in patients with major depressive disorder (MDD). This study investigated whether these effects associate with reversible white matter fiber integrity recovery using diffusion imaging. Twenty patients with MDD and 20 healthy controls received 2-week esketamine treatment. Patients received 0.25 mg/kg intravenous esketamine. Emotional and cognitive recovery were assessed. Diffusion tensor imaging and tract-based spatial statistics evaluated white matter fiber integrity pre/post-treatment. Correlation analyses examined associations between white matter changes and clinical scales. Compared to controls, patients with MDD exhibited decreased fractional anisotropy (FA) values of cerebral white matter fibers involving the association fibers, the commissural fibers and projection fibers. Esketamine effectively reduced depression, anxiety, and suicidal ideation scores while improving cognitive function. However, no reversible recovery of compromised white matter integrity was observed after 2 weeks of esketamine treatment. FA reductions in projection fibers correlated with anxiety and suicidal ideation severity. Concurrent sertraline use and lack of placebo control limited our ability to isolate esketamine's effects. The wide age range may have introduced response variability. We used minimal effective dosages based on previous research. The small sample size limited statistical power. Larger, more controlled studies are needed to validate these preliminary findings. This study enhances MDD neuropathological understanding, with widespread white matter impairment and associations between projection fibers and symptom severity. While producing significant antidepressant effects, short-term esketamine did not recover compromised white matter microstructure. • MDD patients showed widespread white matter deficits across fiber tracts. • Esketamine improved symptoms but not white matter integrity after 2 weeks. • Reduced projection fiber integrity correlated with anxiety and suicidal ideation severity. • Findings shed light on MDD neuropathology and esketamine's mechanisms. [ABSTRACT FROM AUTHOR]
- Published
- 2025
- Full Text
- View/download PDF
37. Modulation of Madden-Julian Oscillation Activity by the Tropical Pacific-Indian Ocean Associated Mode.
- Author
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Li, Lifeng, Li, Xin, Chen, Xiong, Li, Chongyin, Zhang, Jianqi, and Shan, Yulong
- Subjects
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MADDEN-Julian oscillation , *HUMIDITY , *OCEAN , *ZONAL winds , *ATMOSPHERIC circulation , *SOUTHERN oscillation - Abstract
In this study, the impacts of the tropical Pacific-Indian Ocean associated mode (PIOAM) on Madden-Julian Oscillation (MJO) activity were investigated using reanalysis data. In the positive (negative) phase of the PIOAM, the amplitudes of MJO zonal wind and outgoing longwave radiation are significantly weakened (enhanced) over the Indian Ocean, while they are enhanced (weakened) over the central and eastern Pacific. The eastward propagation of the MJO can extend to the central Pacific in the positive phase of the PIOAM, whereas it is mainly confined to west of 160°E in the negative phase. The PIOAM impacts MJO activity by modifying the atmospheric circulation and moisture budget. Anomalous ascending (descending) motion and positive (negative) moisture anomalies occur over the western Indian Ocean and central-eastern Pacific (Maritime Continent and western Pacific) during the positive phase of the PIOAM. The anomalous circulation is almost the opposite in the negative phases of the PIOAM. This anomalous circulation and moisture can modulate the activity of the MJO. The stronger moistening over the Indian Ocean induced by zonal and vertical moisture advection leads to the stronger MJO activity over the Indian Ocean in the negative phase of the PIOAM. During the positive phase of the PIOAM, the MJO propagates farther east over the central Pacific owing to the stronger moistening there, which is mainly attributable to the meridional and vertical moisture advection, especially low-frequency background state moisture advection by the MJO's meridional and vertical velocities. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
38. Characterization and implications of the lingual process of the sphenoid bone: a cadaveric and radiographic study.
- Author
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Li, Lifeng, London, Nyall R., Chen, Xiaohong, Prevedello, Daniel M., and Carrau, Ricardo L.
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SPHENOID bone , *SPHENOID sinus , *STANDARD deviations , *LIGAMENTS - Abstract
Background: The surgical significance of the lingual process of the sphenoid bone (LPSB) has not been sufficiently addressed. The purpose of this study was to describe the anatomical details of the LPSB in relation to the quadrangular space. Moreover, the incidence of the LPSB and its correlation with the pneumatization of the sphenoid sinus and the development of the lateral recess of the sphenoid sinus (LRSS) were also evaluated. Methods: A dissection and exposure of the LPSB and the quadrangular space was performed on 10 cadaveric specimens (20 sides). The incidence, length, and height of the LPSB were also assessed on computed tomography (CT) images (60 patients, 120 sides). The association between the presence of the LPSB with the pneumatization type of the sphenoid sinus and the presence of a LRSS was evaluated. Results: In a cadaveric model, the LPSB, in association with the petrolingual ligament extending from the LPSB to the petrous apex, was identified on 7 sides (35%). The LPSB was continuous with the mandibular strut. The overall incidence of a LPSB was 48.33% on CT images, and the average length and height of the LPSB was (mean ± standard deviation) 5.30 ± 1.44 mm and 6.51 ± 1.32 mm, respectively. A significant correlation was identified between presence of the LPSB with the pneumatization type of the sphenoid sinus (p = 0.004) but no correlation was identified with the presence of the LRSS (p = 0.071). Conclusion: The LPSB and the petrolingual ligament are useful landmarks for procedures in the quadrangular space and Meckel's cave. However, the LPSB is not consistently present. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
39. Effects of various modeling uncertainty parameters on the seismic response and seismic fragility estimates of the aging highway bridges.
- Author
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Li, Huihui, Li, Lifeng, Zhou, Guojie, and Xu, Liang
- Subjects
- *
SEISMIC response , *BRIDGES , *BRIDGE bearings , *LATIN hypercube sampling , *UNCERTAINTY - Abstract
This paper proposes an alternative time-dependent seismic fragility assessment framework for aging highway bridges considering the non-uniform chloride-induced corrosion and various modeling uncertainty parameters. Firstly, sensitivity analysis with the tornado diagram technique is performed to determine the sensitivity of some typical bridge engineering demand parameters (EDPs) to 22 modeling related uncertain parameters, and then 10 critical parameters are identified. Subsequently, based on a series of nonlinear time history analyses (NLTHAs) on the sample models generated by using the Latin hypercube sampling (LHS) method, comparative studies for the time-invariant and time-evolving seismic response, as well as the time-dependent seismic fragility estimates incorporating different levels of uncertainty are performed, respectively. It is concluded that (1) the uncertainty of the modeling related uncertain parameters may lead to the difference in the trajectory of seismic hysteretic response for a given bridge member, whereas the variation of the peak value of seismic response may result from the couple contributions of the uncertainty of ground motions and modeling related parameters; (2) the inclusion of only ground motion uncertainty is inadequate and inappropriate, and the proper way is to incorporate the uncertainty of the identified critical modeling parameters and ground motions into the time-evolving seismic response and the time-dependent seismic fragility assessment of the deteriorating highway bridges. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
40. Temperature-based optical design, optimization and economics of solar polar-field central receiver systems with an optional compound parabolic concentrator.
- Author
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Li, Lifeng, Wang, Bo, Pye, John, and Lipiński, Wojciech
- Subjects
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COMPOUND parabolic concentrators , *SOLAR receivers , *HIGH temperatures , *ECONOMIC systems , *ECONOMICS , *MONTE Carlo method , *RECEIVER operating characteristic curves - Abstract
• Solar central receiver systems with a polar field and an optional CPC are studied. • Effects of geometrical parameters on energetic and economic performance are explored. • Optimal performance for selected receiver temperatures (600–1800 K) are obtained. • Overall minimum levelized cost of exergy is obtained by a no-CPC system at 900 K. • A CPC benefits energetic and economic performance for receiver temperatures >900 and 1200 K, respectively. Energetic and economic characteristics are studied for solar central receiver systems consisting of a polar heliostat field, a tower, a single-aperture cavity receiver, and an optional compound parabolic concentrator (CPC). System characterization and optimization are performed with a numerical model combining an in-house developed Monte-Carlo ray-tracing optical model, a simplified receiver heat transfer model, and a cost model based on the System Advisor Model (SAM). Based on the model, the effects of receiver temperature on the optical configuration of cost-optimal systems are elucidated, along with the benefits of using a CPC for improved energetic and economic performance. Under the assumptions made in this study, it is found that the overall minimum levelized cost of exergy is obtained by a non-CPC system with a receiver operated at approximately 900 K. A CPC benefits both the energetic and economic performance of systems only at elevated temperatures. The working temperature thresholds at which the energetic and economic performance benefit from the addition of a CPC are identified as 900 K and 1200 K, respectively. The general formulation of the model and broad range of values of the investigated parameters provide a universal predictive capability for studying techno-economic performance of concentrating solar thermal systems. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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41. Synthesis of single-hole signatures by group delay for ground vibration control in rock blasting.
- Author
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Li, Lifeng and Silva-Castro, Jhon
- Subjects
- *
SOIL vibration , *BLASTING , *INNER cities , *COAL mining , *SIGNAL processing , *PREDICTION models - Abstract
Prediction and control of ground vibrations become essential as with the development of neighborhoods in the proximity of active mining operations or the need for new infrastructure in urban centers, both requiring the use of blasting. Novel ground vibration prediction models attempt to reproduce a whole vibration waveform from a blast and are based, in most cases, on the collection of vibrational information from a single blasthole. A single blasthole should have the same characteristics (geometry and weights of explosives) as the blastholes used in production shots. In some cases, the collection of the fundamental information (the signature) is straightforward. In more complex cases, the fundamental information from ground vibration data is collected from previous production shots. This study presents a novel methodology to assess the fundamental ground vibration information (the signature) using known information such as one event waveform (a production shot waveform) and the timing sequence used (the comb function) for the shot. The methodology is based on the analysis of group delay, a concept widely used in signal processing, and is modified here for the analysis of ground vibration waveforms. The methodology is developed using real data collected in coal and quarry mining operations, and at the end of this document, one case study with step-by-step calculations is presented to show the benefits of the methodology. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
42. Seismic fragility assessment framework for highway bridges based on an improved uniform design-response surface model methodology.
- Author
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Li, Huihui, Li, Lifeng, Wu, Wenpeng, and Xu, Liang
- Subjects
- *
BRIDGES , *CONCRETE beams , *REINFORCED concrete , *NONLINEAR functions - Abstract
This paper proposes an improved uniform design (UD)-response surface model (RSM) method to reduce the impacts of sample correlation among small sample data caused by UD method and variable substitution process in the traditional UD-RSM method. The proposed B-spline-PLS-UD-RSM method, which is a systematic approach that combines nonlinear B-spline functions, the conventional UD-RSM method and the partial least-squares (PLS) regression technique, assesses the reliability of structures with high nonlinearity and multi-dimensionality. First, two reliability examples from the literature are investigated to demonstrate the efficiency and accuracy of the proposed RSM method. Subsequently, to investigate the applicability of the proposed method in seismic fragility analyses considering various parameter uncertainties and variable correlation, an alternative seismic fragility assessment framework is developed for highway bridges. Furthermore, this paper uses a typical multi-span reinforced concrete continuous girder (MSRCCG) bridge as a case study and performs a comparative analysis of the corresponding seismic fragility evaluations at both bridge component and system levels by using traditional and improved RSM methods. The results indicate the following conclusions: (1) The proposed B-spline-PLS-UD-RSM method can properly reduce the effect of sample correlation and achieve satisfactory reliability results for structures with highly nonlinear and multi-dimensional features through a much smaller sample size; (2) The proposed seismic fragility assessment framework is a good candidate for evaluating the seismic vulnerability of highway bridges incorporating variable correlation of structural parameters; (3) Seismic fragilities of bridge structures tend to be overestimated by using traditional UD-RSM methods and by ignoring the variable correlation of structural random parameters. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
43. Effect of AQP4-RNAi in treating traumatic brain edema: Multi-modal MRI and histopathological changes of early stage edema in a rat model.
- Author
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Guan, Ying, Li, Lifeng, Chen, Jianqiang, and Lu, Hong
- Subjects
- *
CEREBRAL edema , *AQUAPORINS , *EDEMA , *BRAIN injuries , *RATS - Abstract
Traumatic brain injury (TBI) is one of the leading causes of mortality and permanent disabilities worldwide. Brain edema following TBI remains to be the predominant cause of mortality and disability in patients worldwide. Previous studies have reported that brain edema is closely associated with aquaporin-4 (AQP4) expression. AQP4 is a water channel protein and mediates water homeostasis in a variety of brain disorders. In the current study, a rat TBI model was established, and the features of brain edema following TBI were assessed using multimodal MRI. The results of the multimodal MRI were useful, reliable and were used to evaluate the extent and the type of brain edema following TBI. Brain edema was also successfully alleviated using an intracerebral injection of AQP4 small interfering (si)RNA. The expression of AQP4 and its role in brain edema were also examined in the present study. The AQP4 siRNA was demonstrated to downregulate AQP4 expression following TBI and reduced brain edema at the early stages of TBI (6 and 12 h). The current study revealed the MRI features of brain edema and the changes in AQP4 expression exhibited following TBI, and the results provide important information that can be used to improve the early diagnosis and treatment of brain edema. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
44. Distribution Pattern of Anchorage Stress and Water Sensitivity Analysis of Red Clay.
- Author
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Li, Lifeng, Gong, Weili, Deng, Huilin, Zhang, Xiaohu, and Li, Gan
- Subjects
- *
WATER analysis , *LEAD in water , *CLAY , *SENSITIVITY analysis , *ANCHORAGE (Structural engineering) , *SHEAR strength of soils - Abstract
Red clay is a special soil layer with complex engineering properties distributed in tropical and subtropical regions. An anchor cable support is a common form of red clay slope support. The effectiveness of the anchor cable support is mainly determined by the anchoring force provided by the red clay stratum. Increase of the water content will lead to the rapid deterioration of the mechanical properties of red clay, which will lead to the reduction of the anchoring force of the slope anchor cable and lead to the failure of the support. Based on the classical Phillips and uniform anchorage shear stress distribution theory, this paper puts forward a uniform-exponential distribution pattern of anchorage shear stress according to the specific characteristics of red clay by using the characteristics of the peak shear strength and residual shear strength of the rock and soil mass. With increasing anchorage force, the dynamic evolution (single exponential distribution ⟶ double single exponential distribution ⟶ uniform index exponential complex distribution ⟶ uniform distribution) of the anchorage shear stress is analysed. Based on the peak and residual test of the cohesive force and internal friction angle, the relationship between the anchoring force and buried depth and water content is established by analysing the factors influencing the anchoring force. It can be found from the field test that, according to the relationship established, the limit anchorage force of the anchor cable in the red clay stratum can be calculated and the water sensitivity of the anchor cable's limit anchorage force can be quantitatively analysed. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
45. A critical review on shear performance of joints in precast Ultra-High-Performance Concrete (UHPC) segmental bridges.
- Author
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Ye, Meng, Li, Lifeng, Pei, Bida, Yoo, Doo-Yeol, Li, Huihui, and Zhou, Cong
- Subjects
- *
HIGH strength concrete , *STRAINS & stresses (Mechanics) , *SUSTAINABLE construction , *SHEAR strength , *PRECAST concrete , *DATABASE design , *DATABASES - Abstract
Precast Ultra-High-Performance Concrete (UHPC) segmental bridges (PUSBs) are among the most promising structural systems owing to their potential for application in advanced philosophies, such as green and intelligent construction technology, industrialization, prefabrication, and automation. The joints, where precast segments are connected, play a significant role in the construction and structural performance of PUSBs. This study reviews the state-of-the-art knowledge on the shear behavior of UHPC joints, which includes the following aspects: (1) the introduction of joints in PUSBs, including their role, types, experimental methods, and typical shear responses; (2) the development of the experimental database of the push-off tests conducted on UHPC joints; (3) a discussion of the influence of critical factors (e.g., UHPC strength, joint type, confining stress, fiber characteristics, and shear key design) on the shear behavior of UHPC joints; (4) a summary and evaluation of the current analytical models and formulae for predicting the shear resistance of UHPC joints; and (5) the identification of current challenges and recommendations of future research directions for UHPC joints. This review is expected to comprehensively understand the shear performance of UHPC joints and facilitate the research and application of UHPC structures. [Display omitted] • A state-of-the-art review is conducted on the shear performance of joints in precast UHPC members. • The critical factors affecting the shear behavior of UHPC joints are discussed. • Analytical models for predicting the shear strength of UHPC joints are summarized and compared. • Existing formulae for the shear strength of UHPC joints are evaluated based on the experimental database. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
46. Impact of posterior septum resection on nasal airflow pattern and warming function.
- Author
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Li, Lifeng, London, Nyall R., Zang, Hongrui, and Han, Demin
- Subjects
- *
AERODYNAMICS , *COMPUTED tomography , *DYNAMICS , *NASAL cavity , *NOSE diseases , *SHEAR (Mechanics) , *PHYSIOLOGICAL stress , *TEMPERATURE , *NASAL septum - Abstract
Background: The functional significance of the posterior segment of the septum is not fully understood. Aims/Objectives: The purpose of this study was to evaluate the impact of posterior septum resection with varying extents on nasal airflow pattern and warming function, and to determine the appropriate resection extent on posterior septum without disturbing airflow pattern. Material and Methods: Three dimensional models were established from the nasal CT scan of a healthy female volunteer without nasal disease. The models included the normal, as well as 1 cm, 2 cm, and 3 cm extent of posterior septum resection by virtual surgery. Using computational fluid dynamics, the airflow characteristics such as average and peak airflow velocity, average wall shear stress, average temperature and turbulence kinetic energy were recorded and compared among the four models. Results: By comparison with the normal model, the virtual surgeries with varying extents of posterior septum resection (1 cm, 2 cm, and 3 cm), demonstrated little alteration on indices of the average and peak airflow velocity, average wall shear stress, airflow temperature and turbulence kinetic energy. However, a statistical difference of the abovementioned indices existed when compared between varying planes of the nasal cavity (p <.001), although this did not appear to be significantly influenced by the degree of posterior septectomy. Conclusions and significance: From an aerodynamics perspective, little disturbance on airflow pattern and warming function of nasal cavity could be detected with increasing resection of posterior septum (up to 3 cm). These results may imply that resection of the posterior septum (up to 3 cm) has little impact on nasal function. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
47. Endoscopic prelacrimal approach to lateral recess of sphenoid sinus: feasibility study.
- Author
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Li, Lifeng, London, Nyall R., Prevedello, Daniel M., and Carrau, Ricardo L.
- Subjects
- *
SPHENOID sinus , *PTERYGOPALATINE ganglion , *FEASIBILITY studies , *CEREBROSPINAL fluid , *NERVES - Abstract
Background: Various pathologies, including cerebrospinal fluid leaks and meningoencephaloceles, may arise in the lateral recess of the sphenoid sinus (LRSS), which may be accessed via an endonasal transpterygoid approach. The objective of this study was to evaluate the feasibility of accessing the LRSS via an endoscopic prelacrimal approach. Furthermore, we hypothesized that this approach may protect the pterygopalatine ganglion and vidian nerve. Methods: Five cadaveric heads (9 sides) with a well‐pneumatized LRSS were identified and an endonasal prelacrimal approach was performed. The infraorbital nerve, at the orbital floor, served as a critical landmark. After identification of the foramen rotundum at the pterygoid base, the vascular compartment of the pterygopalatine fossa and the pterygopalatine ganglion were displaced inferomedially and superomedially, respectively. Drilling of the bone inferomedial to the foramen rotundum allowed entry into the LRSS. Results: The average distances from the prelacrimal window to the pterygoid base and the posterior wall of the LRSS were 6.22 ± 0.39 cm and 7.16 ± 0.50 cm, respectively. The average areas of the bony prelacrimal window and pterygoid base window were 4.33 ± 0.32 cm2 and 0.73 ± 0.10 cm2, respectively. The LRSS could be accessed using a 0‐degree endoscope, and pterygopalatine neurovascular structures, including the pterygopalatine ganglion and vidian nerve, could be preserved on all 9 sides. Conclusion: Our findings suggest that an endonasal prelacrimal approach provides a reasonable alternative to access the LRSS while preserving the vidian nerve and pterygopalatine ganglion. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
48. Free thyroxine level is associated with both relapse rate and poor neurofunction in first-attack Neuromyelitis Optica Spectrum Disorder (NMOSD) patients.
- Author
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He, Qianyi, Li, Lifeng, Li, Yanfei, Lu, Yanhui, Wu, Kaimin, Zhang, Ruiyi, Teng, Junfang, Zhao, Jie, and Jia, Yanjie
- Subjects
- *
NEUROMYELITIS optica , *THYROXINE , *SCATTER diagrams , *MULTIVARIATE analysis , *REGRESSION analysis - Abstract
Background: To investigate whether the serum free thyroxine (FT4) level is a prognostic factor for the first-attack neuromyelitis optica spectrum disorders (NMOSD).Methods: This retrospective study enrolled 109 patients with first-attack NMOSD. The Expanded Disability Status Scale (EDSS) and the relapse rate were used to evaluate the outcomes. The logistic regression model was used to analyze the independent effects of FT4 on relapse and final EDSS. Kaplan-Meier analysis, scatter plot smoothing method, and two-phase piecewise linear regression model were used to investigate the relationship between the FT4 level and the relapse rate.Results: Multivariate analysis revealed that serum FT4 level might be a risk factor for both final EDSS (β = 0.17; 95% confidence interval: 0.03-0.32) and the relapse rate (HR = 1.18; 95% confidence interval: 1.05-1.32). Furthermore, 1400 days after the onset, nearly 100% of patients in the high-FT4 group relapsed, while only 40% of the patients in the low-FT4 group relapsed. Finally, we found that the relationship between the FT4 level and the NMOSD relapse rate was nonlinear. The risk of NMOSD relapse increased with the FT4 level up to the inflection point of 12.01 pmol/L (HR = 1.45; 95% confidence interval: 1.06-1.98). When the FT4 level was > 12.01 pmol/L, there was no correlation between the FT4 level and the risk of NMOSD relapse (HR = 1.05; 95% confidence interval: 0.78-1.41).Conclusion: Serum FT4 level may be a prognostic indicator for the first-attack in patients with NMOSD. High FT4 levels are associated with poor neurofunctions and a high relapse rate in patients with the first-attack in patients with NMOSD. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
49. Reflective optics for redirecting convergent radiative beams in concentrating solar applications.
- Author
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Li, Lifeng, Wang, Bo, Bader, Roman, Zapata, José, and Lipiński, Wojciech
- Subjects
- *
MONTE Carlo method , *OPTICS , *SOLAR radiation , *RADIATION sources , *SOLAR system , *DEGREES of freedom , *SPECTRAL irradiance , *OPTICAL reflectors - Abstract
• Flat and curved reflectors are investigated for redirecting convergent radiative beams. • Monte Carlo ray-tracing optical simulations are employed. • Optical characteristics of output beams are discussed. • Benefits and disadvantages of the investigated reflectors are explored. We investigate optical characteristics of flat, ellipsoidal, hyperboloidal, and paraboloidal reflectors for redirecting convergent radiative beams common in concentrating solar applications. Optical simulations are performed with selected types of radiative sources including a generic uniformly-emitting spherical cap and a specific realization of a multi-source high-flux solar simulator. Two-dimensional ray-tracing simulations are conducted for an ideal optical system without optical imperfections consisting of a spherical cap source, a beam-redirecting reflector, and a target tailored to capture all radiation. System optical performance is evaluated in terms of output beam optical characteristics of rim angle, ray distribution and relative position to the input beam. Three-dimensional Monte-Carlo ray-tracing simulations are performed for a practical optical system with a realistic solar simulator as radiation source and the four beam-redirecting reflectors. We predict optical characteristics of resulting radiative power, spatial and directional flux distribution, optical efficiencies on specified flat and hemispherical targets, and clearance between simulator, reflector and target. From the model system with a solar simulator and exemplary parameters, it is concluded that the investigated four types of reflectors enable redirection of the horizontal-axis beam from the solar simulator to non-horizontal axis targets. The flat reflector enables the highest system optical efficiency of 97% at the expense of the smallest clearance between the source, the reflector and the reflected image. Curved reflectors render a larger degree of freedom to design the characteristics of the output beam. Thus, curved reflectors are suitable for applications that require large clearance between system components and/or high radiative flux output on cavity surface, but at the expense of lower system optical efficiency. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
50. Transnasal prelacrimal approach to the inferior intraconal space: a feasibility study.
- Author
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Li, Lifeng, London, Nyall R., Silva, Samuel, Prevedello, Daniel, and Carrau, Ricardo L.
- Subjects
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OCULOMOTOR nerve , *OPHTHALMIC artery , *OPTIC nerve , *FEASIBILITY studies , *SPACE frame structures - Abstract
Background: Endonasal access to the inferomedial and inferolateral intraconal space via the orbital floor has not been reported. The primary purpose of this study was to assess the feasibility of accessing the inferior intraconal space through the orbital floor via a transnasal prelacrimal approach. Secondarily, it aims to highlight anatomical relationships of neurovascular structures in this space, as a requirement to prevent complications. Methods: Six cadaveric heads (12 sides) were dissected using a transnasal prelacrimal approach. The orbital floor, medial to the infraorbital canal, was removed and the periorbita opened to expose the inferior rectus muscle. The inferomedial and inferolateral intraconal space was accessed alongside the medial and lateral border of inferior rectus muscle, respectively. Various anatomical relationships of adjacent neurovascular structures were recorded, and the distances among the recti muscles and optic nerve were also measured. Results: The infraorbital nerve is located at the inferolateral aspect of inferior rectus muscle. In the inferomedial intraconal space, we identified the inferomedial muscular trunk of the ophthalmic artery, optic nerve, and branches of the oculomotor nerve; whereas the inferolateral intraconal space contained the inferolateral muscular trunk of ophthalmic artery, branches of the oculomotor and nasociliary nerve, and abducens nerve. Distances from the medial, inferior, and lateral recti muscles to the optic nerve were (mean ± standard deviation) 4.70 ± 1.18 mm, 5.60 ± 0.93 mm, and 7.98 ± 1.99 mm, respectively. Distances from the inferior rectus muscle to the inferior borders of medial and lateral recti muscles were 4.45 ± 1.23 mm and 8.77 ± 1.80 mm. Conclusion: It is feasible to access the inferior intraconal space through the orbital floor via a transnasal prelacrimal approach. The access may be subdivided into inferomedial and inferolateral corridors according to the entry point at the medial or lateral border of the inferior rectus muscle. Neurovascular structures in the inferior intraconal space are visualized directly, which should enhance their preservation. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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