467 results on '"Qingguo, Meng"'
Search Results
2. Improving the Characteristics of Fruiting Bodies in Lentinus edodes: The Impact of Rolipram-Induced cAMP Modulation
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Hongman Li, Fei Chen, Chong Xu, Yanhua Wang, Chunhai Deng, Qingguo Meng, and Weiwei Zhu
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Lentinula edodes ,metabolomics ,exogenous inducers ,fruiting body ,gill-free ,Microbiology ,QR1-502 - Abstract
Background: Strains XG04 and XGT2 of Lentinus edodes (Berk.) Singer demonstrate a high degree of genomic similarity, with XGT2 representing a systematic selection of XG04 and exhibiting enhanced phenotypic traits. Methods: An investigation into the differences between these strains was conducted using untargeted metabolomics to identify potential causal factors. Five exogenous inducers were assessed for their relationship with the observed phenotypes, and their impacts on fruiting body characteristics were analyzed. Results: Notably, the exogenous inducer rolipram, at a concentration of 0.4%, was found to increase cAMP expression levels in L. edodes primordia, which subsequently affected gill development, leading to the formation of gill-free fruiting bodies. Morphological differences between the two strains were evident; XG04 exhibited a spherical morphology with absent gills, rendering it commercially unviable, whereas XGT2 displayed a thicker cap and a more robust stipe, maintaining its characteristic umbrella shape. Conclusions: As the concentration of rolipram increased, both cap retraction and gill reduction in XGT2 occurred in a dose-dependent manner. The endogenous cAMP levels in the fruiting bodies were measured before and after rolipram treatment, revealing that the cap retraction and gill reduction in XGT2 progressed in a dose-dependent manner alongside increasing cAMP expression levels. Furthermore, a positive correlation was observed between cAMP levels and rolipram concentration. This study provides a foundation for improving the quality and productivity of mushroom cultivation by manipulating fruiting body characteristics through external stimuli.
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- 2024
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3. Empowering the Online Media System: The Innovative Route of Effective Digital Government Response in China
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Zipeng Li and Qingguo Meng
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digital government ,government response ,government website ,the media system dependence ,media mechanism ,Business ,HF5001-6182 - Abstract
Studies on the Chinese government’s online response present diverse voices and perspectives, but consensus cannot be reached. The literature has constantly ignored the construction of an online media mechanism, which includes professional positions and standardized procedures that were designed inside the online media to process information and facilitate an effective government response. Does the reconstruction of an online media mechanism benefit the effectiveness of government response? If so, how? From the perspective of the media mechanism, what are the influential factors for the effectiveness of government response and how do they work to exert this impact? Engaging with the media system dependence theory, I conducted semi-structured, in-depth interviews with the editor at the Beijing Municipal Government Website and official document drafters at prestigious research institutions. In conversation with the political system theory, multinomial logistic regression was used to analyze the daily government response data covering the period from 2019 to 2020. This article argues that the innovations in the mechanism inside the online media system can outsource some information management functions from the political system to the online media system. These innovations also assist in partial power transfer from the political system to the media system to achieve an effective government response. The political system faces dual pressure, including content pressure and time pressure, regarding its online response.
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- 2023
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4. Molecular Dynamics Simulation of the Three-Phase Equilibrium Line of CO2 Hydrate with OPC Water Model
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Xiluo Hao, Chengfeng Li, Qingguo Meng, Jianye Sun, Li Huang, Qingtao Bu, and Congying Li
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Chemistry ,QD1-999 - Published
- 2023
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5. Does the Citizen's Education Level and Digital Information Ability Affect their Internet Rights Protection Willingness?
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Yuanyuan Guo, Yi Deng, and Qingguo Meng
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- 2023
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6. Rapid Screening of Carotid Plaque in Cloud Handheld Ultrasound System Based on 5G and AI Technology
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Wenjun Zhang, MD, Mi Zhou, PhD, Qingguo Meng, MD, Lin Zhang, MS, Xin Liu, MS, Paul Liu, PhD, Dong Liu, PhD
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handheld ultrasound ,carotid plaque ,yolov3 ,artificial intelligence (ai) ,Medical technology ,R855-855.5 ,Medicine - Abstract
Objective: To evaluate the real-time accuracy of cloud handheld ultrasound system using AI technology in screening carotid plaque. Methods: 2627 ultrasound images of the carotid artery are collected using the cloud handheld system. Bounding boxes of carotid plaques are labeled by qualified sonographers, and the dataset is trained using a lightweight YOLOv3 model. An additional and separate 390 images are collected and tested using the evaluation metrics average recall (AR), average precision (AP), and frames per second (FPS) for quantifying classification performance and time consumption. Results: We use a plaque grading definition with a thickness of 1.2-1.5 mm defined as small plaque, 1.5-3 mm as medium plaque, and more than 3 mm thick as large plaque. Our model achieves APIoU=0.50 with 96.5%, with APlarge is 79.9%, APmedium is 90.7%, APsmall is 93.5%; ARIoU=0.50 is 64.5%, where ARlarge is 60.6%, ARmedium is 58.3%, ARsmall is 70.8%, and FPS is 33.3. Conclusion: We establish a framework for data set construction, model selection, training, and testing of carotid ultrasound images and verify the effectiveness of real-time AI technology in the automatic detection of carotid artery plaque.
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- 2023
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7. How Does the Citizen's Education Level Affect Their Internet Rights Protection Willingness? - - The Parallel Intermediary Effect of Digital Information Acquisition Ability and Utilization Ability.
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Yuanyuan Guo, Yi Deng, and Qingguo Meng
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- 2023
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8. Pore Water Conversion Characteristics during Methane Hydrate Formation: Insights from Low-Field Nuclear Magnetic Resonance (NMR) Measurements
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Jiaxian Wang, Yunkai Ji, Changling Liu, Qingguo Meng, Yapeng Zhao, Zhun Zhang, Jianye Sun, Lele Liu, and Fulong Ning
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methane hydrate ,unconsolidated sand ,low-field NMR ,mass transfer ,conversion rate of pore water ,final conversion ratio of pore water ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 ,Oceanography ,GC1-1581 - Abstract
Understanding the conversion characteristics of pore water is crucial for investigating the mechanism of hydrate accumulation; however, research in this area remains limited. This study conducted methane hydrate formation experiments in unconsolidated sands using an in-house low-field nuclear magnetic resonance (NMR) system. It focused on pore water conversion characteristics and influencing factors such as initial water saturation and sand particle sizes. Results show that methane hydrate formation enhances the homogeneity of the effective pore structure within sand samples. The conversion rate of pore water is significantly influenced by differences in heat and mass transfer capacity, decreasing as initial water saturation and sand size increase. Pore water cannot be fully converted into hydrates in unconsolidated sands. The final conversion ratio of pore water in water-poor sand samples nears 97%, while in water-rich sand samples, it is only 65.80%. Sand particle size variation has a negligible impact on the final conversion ratio of pore water, with ratios exceeding 94% across different particle sizes, differing by less than 3%.
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- 2024
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9. Research Advances in Clinical Applications, Anticancer Mechanism, Total Chemical Synthesis, Semi-Synthesis and Biosynthesis of Paclitaxel
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Shengnan Zhang, Taiqiang Ye, Yibin Liu, Guige Hou, Qibao Wang, Fenglan Zhao, Feng Li, and Qingguo Meng
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paclitaxel ,anticancer mechanism ,total synthesis ,semi-synthesis ,biosynthesis ,Organic chemistry ,QD241-441 - Abstract
Paclitaxel, a natural secondary metabolite isolated and purified from the bark of the Taxus tree, is considered one of the most successful natural anticancer drugs due to its low toxicity, high potency and broad-spectrum anticancer activity. Taxus trees are scarce and slow-growing, and with extremely low paclitaxel content, the contradiction between supply and demand in the market is becoming more and more intense. Therefore, researchers have tried to obtain paclitaxel by various methods such as chemical synthesis, artificial culture, microbial fermentation and tissue cell culture to meet the clinical demand for this drug. This paper provides a comprehensive overview of paclitaxel extraction, combination therapy, total synthesis, semi-synthesis and biosynthesis in recent years and provides an outlook, aiming to provide a theoretical basis and reference for further research on the production and application of paclitaxel in the future.
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- 2023
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10. The role of potential probiotic strains Lactobacillus reuteri in various intestinal diseases: New roles for an old player
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Zihan Yu, Jihua Chen, Yaxin Liu, Qingguo Meng, Hang Liu, Qinyan Yao, Wenxuan Song, Xiangfeng Ren, and Xin Chen
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Lactobacillus reuteri ,intestinal diseases ,gut microbiota ,inflammatory bowel disease ,colorectal cancer ,Microbiology ,QR1-502 - Abstract
Lactobacillus reuteri (L. reuteri), a type of Lactobacillus spp., is a gut symbiont that can colonize many mammals. Since it was first isolated in 1962, a multitude of research has been conducted to investigate its function and unique role in different diseases as an essential probiotic. Among these, the basic functions, beneficial effects, and underlying mechanisms of L. reuteri have been noticed and understood profoundly in intestinal diseases. The origins of L. reuteri strains are diverse, with humans, rats, and piglets being the most common. With numerous L. reuteri strains playing significant roles in different intestinal diseases, DSM 17938 is the most widely used in humans, especially in children. The mechanisms by which L. reuteri improves intestinal disorders include protecting the gut barrier, suppressing inflammation and the immune response, regulating the gut microbiota and its metabolism, and inhibiting oxidative stress. While a growing body of studies focused on L. reuteri, there are still many unknowns concerning its curative effects, clinical safety, and precise mechanisms. In this review, we initially interpreted the basic functions of L. reuteri and its related metabolites. Then, we comprehensively summarized its functions in different intestinal diseases, including inflammatory bowel disease, colorectal cancer, infection-associated bowel diseases, and pediatric intestinal disorders. We also highlighted some important molecules in relation to the underlying mechanisms. In conclusion, L. reuteri has the potential to exert a beneficial impact on intestinal diseases, which should be further explored to obtain better clinical application and therapeutic effects.
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- 2023
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11. Phytochemistry, health benefits, and food applications of sea buckthorn (Hippophae rhamnoides L.): A comprehensive review
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Zhen Wang, Fenglan Zhao, Panpan Wei, Xiaoyun Chai, Guige Hou, and Qingguo Meng
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sea buckthorn ,phytochemistry ,nutrients ,health benefits ,food applications ,Nutrition. Foods and food supply ,TX341-641 - Abstract
Sea buckthorn (Hippophae rhamnoides L.), an ancient miraculous plant, is of great interest because of its tenacity, richness in nutritional active substances, and biological activity. Sea buckthorn is a deciduous shrub or tree of the genus Hippophae in the family Elaeagnaceae. It is a pioneer tree species for soil improvement, wind and sand control, and soil and water conservation. Sea buckthorn contains many nutritional active components, such as vitamins, carotenoids, polyphenols, fatty acids, and phytosterols. Moreover, sea buckthorn has many health benefits, such as antioxidant, anticancer, anti-hyperlipidemic, anti-obesity, anti-inflammatory, antimicrobial, antiviral, dermatological, neuroprotective, and hepatoprotective activities. Sea buckthorn not only has great medicinal and therapeutic potential, but also is a promising economic plant. The potential of sea buckthorn in the human food industry has attracted the research interest of researchers and producers. The present review mainly summarizes the phytochemistry, nutrients, health benefits, and food applications of sea buckthorn. Overall, sea buckthorn is a dietary source of bioactive ingredients with the potential to be developed into functional foods or dietary supplements for the prevention and treatment of certain chronic diseases, which deserves further research.
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- 2022
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12. Full-length transcriptome sequencing and comparative transcriptome analysis of Eriocheir sinensis in response to infection by the microsporidian Hepatospora eriocheir
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Libo Hou, Mengdi Wang, Lei Zhu, Mingxiao Ning, Jingxiu Bi, Jie Du, Xianghui Kong, Wei Gu, and Qingguo Meng
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Eriocheir sinensis ,third-generation sequencing technology ,microsporidian ,intestine ,hepatopancreatic necrosis disease ,Microbiology ,QR1-502 - Abstract
As a new generation of high-throughput sequencing technology, PacBio Iso-Seq technology (Iso-Seq) provides a better alternative sequencing method for the acquisition of full-length unigenes. In this study, a total of 22.27 gigabyte (Gb) subread bases and 128,614 non-redundant unigenes (mean length: 2,324 bp) were obtained from six main tissues of Eriocheir sinensis including the heart, nerve, intestine, muscle, gills and hepatopancreas. In addition, 74,732 unigenes were mapped to at least one of the following databases: Non-Redundant Protein Sequence Database (NR), Gene Ontology (GO), Kyoto Encyclopaedia of Genes and Genomes (KEGG), KEGG Orthology (KO) and Protein family (Pfam). In addition, 6696 transcription factors (TFs), 28,458 long non-coding RNAs (lncRNAs) and 94,230 mRNA-miRNA pairs were identified. Hepatospora eriocheir is the primary pathogen of E. sinensis and can cause hepatopancreatic necrosis disease (HPND); the intestine is the main target tissue. Here, we attempted to identify the key genes related to H. eriocheir infection in the intestines of E. sinensis. By combining Iso-Seq and Illumina RNA-seq analysis, we identified a total of 12,708 differentially expressed unigenes (DEUs; 6,696 upregulated and 6,012 downregulated) in the crab intestine following infection with H. eriocheir. Based on the biological analysis of these DEUs, several key processes were identified, including energy metabolism-related pathways, cell apoptosis and innate immune-related pathways. Twelve selected genes from these DEUs were subsequently verified by quantitative real-time PCR (qRT-PCR) analysis. Our findings enhance our understanding of the E. sinensis transcriptome and the specific association between E. sinensis and H. eriocheir infection.
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- 2022
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13. The genome and antigen proteome analysis of Spiroplasma mirum
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Peng Liu, Yuxin Li, Youyuan Ye, Jiaxin Chen, Rong Li, Qinyi Zhang, Yuan Li, Wen Wang, Qingguo Meng, Jingyu Ou, Zhujun Yang, Wei Sun, and Wei Gu
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genome ,antigen proteome ,Spiroplasma mirum ,spiroplasma ,pathogenesis ,Microbiology ,QR1-502 - Abstract
Spiroplasma mirum, small motile wall-less bacteria, was originally isolated from a rabbit tick and had the ability to infect newborn mice and caused cataracts. In this study, the whole genome and antigen proteins of S. mirum were comparative analyzed and investigated. Glycolysis, pentose phosphate pathway, arginine metabolism, nucleotide biosynthesis, and citrate fermentation were found in S. mirum, while trichloroacetic acid, fatty acids metabolism, phospholipid biosynthesis, terpenoid biosynthesis, lactose-specific PTS, and cofactors synthesis were completely absent. The Sec systems of S. mirum consist of SecA, SecE, SecDF, SecG, SecY, and YidC. Signal peptidase II was identified in S. mirum, but no signal peptidase I. The relative gene order in S. mirum is largely conserved. Genome analysis of available species in Mollicutes revealed that they shared only 84 proteins. S. mirum genome has 381 pseudogenes, accounting for 31.6% of total protein-coding genes. This is the evidence that spiroplasma genome is under an ongoing genome reduction. Immunoproteomics, a new scientific technique combining proteomics and immunological analytical methods, provided the direction of our research on S. mirum. We identified 49 proteins and 11 proteins (9 proteins in common) in S. mirum by anti-S. mirum serum and negative serum, respectively. Forty proteins in S. mirum were identified in relation to the virulence. All these proteins may play key roles in the pathogeny and can be used in the future for diagnoses and prevention.
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- 2022
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14. Speckle tracking imaging evaluation of left ventricular myocardial work comparing right ventricular septal pacing with His-Purkinje system area pacing
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Qingguo Meng, Yao Li, Sijia Wang, Tianhang Feng, Huijun Xu, Juan Liu, Xuebing Liu, Zhiyu Guo, Yan Deng, Chunmei Li, Yijia Tang, and Lixue Yin
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myocardial work ,right ventricular septal pacing ,His-Purkinje system area pacing ,constructive work ,work efficiency ,Diseases of the circulatory (Cardiovascular) system ,RC666-701 - Abstract
AimsWe sought to objectively assess left ventricular myocardial work (MW) parameters after right ventricular septal pacing (VSP) and His-Purkinje system area pacing (HPSAP) procedures.Materials and methodsPatients undergoing double-chamber pacemaker implantation for III-degree atrioventricular block (III° AVB) were assessed 1 year after implantation. VSP and HPSAP groups (20 and 23 patients, respectively) were compared against 40 healthy age-matched volunteers. Two-dimensional ultrasound speckle tracking imaging was used to obtain the global myocardial work index (GWI), global myocardial work efficiency (GWE), global myocardial constructive work (GCW), global myocardial wasted work (GWW), left ventricular stratified strain, and peak strain dispersion (PSD).ResultsGWI, GWE, and GCW parameters were improved in HPSAP compared to VSP, while GWW was significantly larger in the VSP group compared to the HPSAP group (all p < 0.05). HPSAP outperformed the VSP group in comparisons of global left ventricular longitudinal strain and stratified strain. Compared to controls, the GCW of all segmental myocardium (17/17 segments) in the VSP group was significantly reduced, while 70.59% (12/17 segments) in the HPSAP group was lower than the control group. GCW in the left ventricular segment of the HPSAP group was bigger than the VSP group (29.41%; 5/17 segments) and mainly concentrated in the ventricular septum and inferior wall.ConclusionOur findings suggest that HPSAP performance outcomes are improved over VSP after 1 year, especially in left ventricular contractile synchrony, and HPSAP is beneficial to the effective myocardial work of the left ventricle.
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- 2022
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15. Development of a rotation and swing torque detection system after bearing installation.
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Qingguo Meng, Zeliang Wang, Jinyao Mu, and Lingchun Kong
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DETECTOR circuits , *ELECTRIC circuits , *TORQUEMETERS , *FRICTION , *ROTATIONAL motion - Abstract
The swing torque and rotational torque after the spherical bearing is installed directly affect the performance of the spherical bearing. At this stage, the friction torque detection equipment of the spherical bearing is mainly used to detect uninstalled bearings. A set of rotation and swing after the bearing is installed is designed. Torque detection system. The detection principles of rotational torque and swing torque required for flexibility detection were analyzed, the functional design requirements and main technical indicators of the detection system were clarified, and the overall design plan of the detection system was established; the host structure of the detection system was designed, including rotational torque detection system, swing torque detection system, clamping system and calibration system; completed the scheme design of the detection control system, selected the torque sensor and servo motor, designed the main electrical control circuit of the detector; conducted error analysis of the detector. [ABSTRACT FROM AUTHOR]
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- 2024
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16. Coal Rock Breaking Simulation and Cutting Performance Analysis of Disc Cutters
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Xu Zhang, Juan Wang, Qingguo Meng, Maolin Yu, Zhenjiang Zhang, and Zhenggang Guo
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coal rock breaking principle ,cutting performance ,disc cutters ,tunnel boring machine (TBM) ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
The coal rock breaking ability of disc cutters directly affects the construction efficiency and safety of rescue tunnels in collapsed coal rock formations. This paper establishes the plastic constitutive relationship under the Drucker-Prager (D-P) plasticity criterion, builds up a finite-element analysis (FEA) model for the coal rock breaking with a single cutter on Abaqus FEA, and explores the influence laws of different penetrations and cutting velocities on the rock breaking performance of the cutter. The results show that: as the penetration increased from 3.0 mm to 7.0 mm, the mean vertical force of the cutter grew from 16.97 kN to 23.36 kN, and the mean rolling force rose from 1.79 kN to 3.95 kN. The increase of the cutter's vertical force improves the cutting efficiency, but intensifies the vertical impact, which undermines construction safety. As the cutting velocity increased from 0.6 rad/s to 1.5 rad/s, the mean vertical force grew from 15.64 kN to 22.94 kN, and the mean rolling force rose from 1.46 kN to 4.23 kN. With the increase of cutting velocity, the cutting force grew at an increasing speed. The increase of cutting velocity can improve cutting efficiency, but an excessively fast cutting velocity will weaken the stability of the cutting operation, and add to the wear of the tool. The research method provides theoretical supports to the cutterhead design of tunnel boring machine (TBM) and tunnelling control in broken coal rock formation.
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- 2021
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17. The distribution pattern of periprostatic neurovascular bundles examined with successive celloidin slices
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Xuemei Li, Jianhui Wu, Qiliang Cai, Janming Pan, Qingguo Meng, Ping Zhang, Yong Xu, and Lidong Zhai
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Prostatic capsule ,Urinary incontinence ,Prostatectomy ,Neurovascular bundles ,Male urethral sphincter ,Detrusor apron ,Diseases of the genitourinary system. Urology ,RC870-923 - Abstract
Abstract Background Although several distribution patterns of periprostatic neurovascular bundles have been proposed, variant dissection technique based on these patterns still confused surgeons. The aim of this study was to describe the periprostatic neurovascular bundles and their relationship with the fascicles around prostate and provide the accurate morphologic knowledge of periprostatic tissue for prostate operation. Methods The pelvic viscera were obtained from 26 adult male cadavers. They were embedded in celloidin and cut into successive slices. The slices were explored with anatomic microscopy. 3-Dimensional reconstruction was achieved with celloidin sections and series software. Results The prostatic capsule which surrounded the dorsal, bilateral aspect of the prostate was attached ventrally to anterior fibrous muscular stroma (AFMS). The lower part of the striated sphincter completely embraced the urethral; the upper part of this muscle covered the lower ventral surface of prostate. The upper ventral surface of prostate is covered by the circular muscle of detrusor. The levator fascia and the capsule adhered on the most convex region of the lateral prostate, but separated on the other region. The pelvic neurovascular bundles (PNVB) divided into the anterior and posterior divisions. The anterior division continued as dorsal vascular complex (DVC). The distal part of DVC entered into penile hilum. The posterior division continued as neurovascular bundles, and then as the cavernous supply (CS). The distal part of CS joined into pudendal neurovascular bundles. Conclusions The capsule and AFMS formed a pocket like complex. There were anterior and posterior neurovascular approaches from PNVB to penile hilum.
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- 2021
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18. The Adjustment of Pressure Perception in E-Government Response: A Perspective of the Political System Theory.
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Zipeng Li, Wenquan Wu, and Qingguo Meng
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- 2023
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19. Citizen preferences and government chatbot social characteristics: Evidence from a discrete choice experiment.
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Jingrui Ju, Qingguo Meng, Fangfang Sun, Luning Liu, and Shweta Singh
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- 2023
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20. PM2.5 Synergizes With Pseudomonas aeruginosa to Suppress Alveolar Macrophage Function in Mice Through the mTOR Pathway
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Jianlong Zhang, Chong Liu, Guangrong Zhao, Meng Li, Di Ma, Qingguo Meng, Wenli Tang, Qingrong Huang, Peimin Shi, Youzhi Li, Linlin Jiang, Xin Yu, Hongwei Zhu, Guozhong Chen, and Xingxiao Zhang
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PM2.5 ,Pseudomonas aeruginosa ,alveolar macrophages ,poultry houses ,mTOR ,Therapeutics. Pharmacology ,RM1-950 - Abstract
High concentrations of PM2.5 in enclosed broiler houses cause respiratory disorders in humans and animals. Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen that can induce severe respiratory disease in animals under stress or with abnormal immune functions. Alveolar macrophages are lung-resident immune cells that play important roles in lung host defence and immune balance. In this study, the mechanism by which PM2.5 synergizes with P. aeruginosa to damage alveolar macrophage function and induce inflammation was investigated. The results will provide a theoretical basis for improving the poultry breeding environment and preventing the recurrence of infection with P. aeruginosa. Alveolar macrophages were stimulated by PM2.5 collected in an enclosed broiler house and P. aeruginosa. Phagocytosis was determined by the neutral red test. The apoptosis rate and cytoskeleton changes were observed by flow cytometry assays and laser scanning confocal microscopy. Protein levels related to autophagy and the mTOR pathway were detected by Western blotting. The results indicated that PM2.5 in combination with P. aeruginosa could decrease phagocytosis, inhibit autophagy, increase apoptosis, and destroy the cytoskeleton in alveolar macrophages. In addition, alveolar macrophages had significantly increased expression of mTOR pathway-related proteins in response to the synergistic stimulation of PM2.5 and P. aeruginosa. The above results confirmed that PM2.5 in poultry houses synergized with P. aeruginosa to impede alveolar macrophage function and caused more severe respiratory system injuries through a process closely related to the activation of the mTOR signalling pathway.
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- 2022
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21. 2-D electrical resistivity tomography assessment of hydrate formation in sandy sediments
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Yanlong Li, Hailiang Sun, Qingguo Meng, Changling Liu, Qiang Chen, and Lanchang Xing
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Natural gas hydrate ,Electrical resistivity ,Electrical conductivity ,Electrical resistance tomography ,Salt-removing effect ,Process monitoring ,Gas industry ,TP751-762 - Abstract
Laboratory hydrate formation process simulation provides a theoretical support for determining the dynamic revolution behaviors of actual hydrate reservoirs. In view of this, based on the ITS electrical resistance tomography (ERT) module, a dedicated apparatus was developed to simulate the in-situ core-scale distribution of natural gas hydrate directly during the process of hydrate formation and dissociation in artificial sediments. Beach sand was used as porous media to simulate the formation of methane hydrate and assess the 2-D ERT evolution characteristics simultaneously. The findings were obtained. (1) The apparent average resistance values of hydrate-bearing sediment system are determined by the combination of hydrate forming rate and salt-removing effect, showing fluctuation rise behaviors during the process of hydrate formation. (2) When the hydrate forming rate is high enough, hysteresis influence of salt-removing effect on apparent average resistance value is observed. After the hydrate formation, there still exists a mass transfer process controlled by the difference of salt ion concentration. (3) Difference between original and real-time ERT distribution indicates a heterogeneous formation process of hydrate within the sediments. In conclusion, initial gas–water contact relationship and distribution is the virtual factors for hydrate heterogeneous distribution behaviors, while that of spatial difference of ion concentration caused by the salt-removing effect plays a key role in promoting local hydrate formation position change.
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- 2020
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22. Protocol for sand control screen design of production wells for clayey silt hydrate reservoirs: A case study
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Yanlong Li, Fulong Ning, Nengyou Wu, Qiang Chen, Alireza Nouri, Gaowei Hu, Jiaxin Sun, Zenggui Kuang, and Qingguo Meng
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clayey silt hydrate reservoir ,gas hydrate ,sand control ,sand production ,screen mesh size ,Shenhu area ,Technology ,Science - Abstract
Abstract The process of extracting natural gas from gas hydrate‐bearing sediments (GHBS) may yield significant sand influx due to the metastable nature of GHBS. Selecting appropriate sand control media is vital to addressing the challenges caused by excessive sand production. This study proposes a protocol called holding coarse expelling fine particles (HCEFP) for sand control design. The protocol aims to provide a new optimization method for screen mesh size selection for clayey silt hydrate reservoirs. Detailed optimizing procedures of proper candidate screen mesh sizes in hydrate exploitation well in clayey silt hydrate reservoirs are depicted based on the HCEFP. Then, the site W18, which is located in the Shenhu area of the northern South China Sea, is taken as an example to illustrate the optimization procedure for screen mesh size selection. The results reveal that complete solid retention via a standalone screen is rarely beneficial as high clay contents can adversely affect wellbore productivity due to excessive plugging. Screen aperture size selection for clayey silt hydrate wells should strike a balance between retaining coarser particles and avoiding screen blockage by the relatively fine particles. Furthermore, longitudinal heterogeneity of the PSDs also increases the difficulties associated with sand control design. Multistage sand control optimization is necessary in hydrate production wells. For Site W18, we recommend that the entire production interval can be divided into two subintervals for multistage sand control operations.
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- 2020
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23. An integrated experimental system for gas hydrate drilling and production and a preliminary experiment of the depressurization method
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Changling Liu, Yanlong Li, Lele Liu, Gaowei Hu, Qiang Chen, Nengyou Wu, and Qingguo Meng
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Gas industry ,TP751-762 - Abstract
The current natural gas hydrate extraction experimental research has always been carried out in a small-scale simulation test device, and the resulted boundary effect is so obvious due to the small size of samples in the reaction kettle that the experimental results will be difficult to apply in the field. In this paper, an integrated experimental system for drilling and exploitation of gas hydrate is developed innovatively based on the idea of depressurization method and the technological process. This experimental system consists of high-pressure vesselmodule, drilling & extraction module, liquid supply module, gas supply module, confining pressure loading module, back-pressure control module, three-phase separation module, temperature control module, data acquisition module and an operational platform. The hydrate-bearing samples similar to marine hydrate formations were prepared inthe experimental system with the actual geological surroundings simulated. The electrical resistance tomography was used to real-time monitor the dynamic distribution of gas hydrate in sediments inside the high-pressure vessel (521 L). This experimental system can also simulate the process of wellbore drilling in hydrate reservoirs and depressurization extraction, and realize the real-time monitoring of parameters in the whole production process such as gas production, water production, sand production, temperature, pressure, etc. We carried out a preliminary experiment on the CO2 hydrate extraction via depressurization by using this experimental system. Fundamental procedures for data acquisition and analysis were established and verified. The variations of temperature and pressure fields and gas/water output behaviors in the reservoirs were both achieved. The results show that (1) the gas and water production rate fluctuate greatly even at a constant backpressure; (2) the reservoir temperature distribution is uneven during hydrate decomposition, and the maximum temperature is decreased by 5 °C, suggesting that the hydrate decomposition is heterogeneous and stochastic. The abundant and credible experimental results based on this system are expected to provide important data support for marine gas hydrate production tests. Keywords: Natural gas hydrate, Experimental system, Drilling and production integration, Real-time monitoring, Depressurization method, CO2 hydrate, Production behavior, Electrical resistance tomography
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- 2020
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24. Advances in the chemistry, pharmacological diversity, and metabolism of 20(R)-ginseng saponins
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Chaoming Wang, Juan Liu, Jianqiang Deng, Jiazhen Wang, Weizhao Weng, Hongxia Chu, and Qingguo Meng
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Botany ,QK1-989 - Abstract
Ginseng has been used as a popular herbal medicine in East Asia for at least two millennia. However, 20(R)-ginseng saponins, one class of important rare ginsenosides, are rare in natural products. 20(R)-ginseng saponins are generally prepared by chemical epimerization and microbial transformation from 20(S)-isomers. The C20 configuration of 20(R)-ginseng saponins are usually determined by 13C NMR and X-ray single-crystal diffraction. 20(R)-ginseng saponins have antitumor, antioxidative, antifatigue, neuroprotective, and osteoclastogenesis inhibitory effects, among others. Owing to the chemical structure and pharmacological and stereoselective properties, 20(R)-ginseng saponins have attracted a great deal of attention in recent years. In this study, the discovery, identification, chemical epimerization, microbial transformation, pharmacological activities, and metabolism of 20(R)-ginseng saponins are summarized. Keywords: 20(R)-ginseng saponin, Epimerization, Identification, Metabolism, Pharmacological activity
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- 2020
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25. Toxicity of avermectin to Eriocheir sinensis and the isolation of a avermectin-degrading bacterium, Ochrobactrum sp. AVM-2
- Author
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Yubo Ma, Hongli Liu, Xiaoli Xia, Mingxiao Ning, Bairu Ji, Yingrui Li, Haolan Li, Jie Du, Wei Sun, Wei Gu, and Qingguo Meng
- Subjects
Avermectin ,Ochrobactrum ,Eriocheir sinensis ,Toxicity ,Degradation characteristics ,Environmental pollution ,TD172-193.5 ,Environmental sciences ,GE1-350 - Abstract
Avermectin is widely used in the prevention and treatment of parasites diseases in aquaculture. However, the residual avermectin has a serious impact on the growth and quality of aquatic animals including Eriocheir sinensis. This study shows that the LC50 of avermectin to E. sinensis for 24, 48, 72 and 96 h was 21.88, 13.40, 9.11 and 7.10 mg/L, respectively. After avermectin stress, the activities of superoxide dismutase (SOD), catalase (CAT) and phenol oxidase (PO) in the hepatopancreas of E. sinensis increased and reached the peak on the 6th day. The content of malondialdehyde (MDA) accumulated with the increase of exposure time and concentration of avermectin. After 15 days of avermectin exposure, hepatopancreas was damaged seriously. These results indicated that avermectin had toxicity to E. sinensis. In order to solve the pollution problem caused by residual avermectin, a degrading bacterium AVM-2 was separated from the sediment of E. sinensis breeding pond. The strain was confirmed to be Ochrobactrum sp by morphology observation, physiological and biochemical identification and 16 S rDNA sequences analysis. When the pH value was 7, the temperature was 30 ℃, the concentration of substrate was low, the quantity of inoculation was high, Ochrobactrum sp. AVM-2 had better degradation effect on avermectin. When the addition of Ochrobactrum sp. AVM-2 was 2.34 × 108 CFU/L, the residual avermectin in muscle and hepatopancreatine significantly decreased, and the degradation rate was about 66%. In summary, Ochrobactrum sp. AVM-2 could be used to solve the residual problem of avermectin and ensure the food safety of E. sinensis.
- Published
- 2022
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26. Dioscorea spp.: Bioactive Compounds and Potential for the Treatment of Inflammatory and Metabolic Diseases
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Zhen Wang, Shengnan Zhao, Siyu Tao, Guige Hou, Fenglan Zhao, Shenpeng Tan, and Qingguo Meng
- Subjects
Dioscorea ,bioactive compounds ,anti-inflammatory activity ,metabolic diseases ,metabolic disorders ,Organic chemistry ,QD241-441 - Abstract
Dioscorea spp. belongs to the Dioscoreaceae family, known as “yams”, and contains approximately 600 species with a wide distribution. It is a major food source for millions of people in tropical and subtropical regions. Dioscorea has great medicinal and therapeutic capabilities and is a potential source of bioactive substances for the prevention and treatment of many diseases. In recent years, increasing attention has been paid to the phytochemicals of Dioscorea, such as steroidal saponins, polyphenols, allantoin, and, in particular, polysaccharides and diosgenin. These bioactive compounds possess anti-inflammatory activity and are protective against a variety of inflammatory diseases, such as enteritis, arthritis, dermatitis, acute pancreatitis, and neuroinflammation. In addition, they play an important role in the prevention and treatment of metabolic diseases, including obesity, dyslipidemia, diabetes, and non-alcoholic fatty liver disease. Their mechanisms of action are related to the modulation of a number of key signaling pathways and molecular targets. This review mainly summarizes recent studies on the bioactive compounds of Dioscorea and its treatment of inflammatory and metabolic diseases, and highlights the underlying molecular mechanisms. In conclusion, Dioscorea is a promising source of bioactive components and has the potential to develop novel natural bioactive compounds for the prevention and treatment of inflammatory and metabolic diseases.
- Published
- 2023
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27. Active Polarization Imaging for Cross-Linear Image Histogram Equalization and Noise Suppression in Highly Turbid Water
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Huajun Zhang, Jianrui Gong, Mingyuan Ren, Ning Zhou, Hantao Wang, Qingguo Meng, and Yu Zhang
- Subjects
underwater imaging ,polarimetric imaging ,high-turbidity water ,histogram equalization ,Applied optics. Photonics ,TA1501-1820 - Abstract
The absorption and scattering of impurity particles in turbid water cause the target signal light to be attenuated and to produce backscattered light, resulting in the reduced quality of underwater polarimetric imaging. As water turbidity increases, the effect of backscattered light becomes greater, making polarization imaging in highly turbid water a challenge. Theory and experiment show that the increase in the intensity of backscattered light leads to high noise gain in the underwater active polarization imaging model. In order to enhance image contrast and suppress noise gain in highly turbid water, we propose an underwater imaging enhancement method that appropriately combines the non-physical and physical models. The method uses contrast limited adaptive histogram equalization (CLAHE) for a certain number of cross-linear images (Imin) before calculating their polarization enhancement images, and it constructs joint filtering (multi-frame averaging and bilateral filtering) to suppress the high noise gain introduced by the imaging model and CLAHE. The experimental results in highly turbid water validate the rationality and feasibility of the proposed method, and the comparative processing results (52.7~98.6 NTU) outperform those of the conventional non-physical and physical model methods. The method maintains the complexity of the system and facilitates the application of conventional polarimetric imaging in harsher underwater environments.
- Published
- 2023
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28. Resection of small acoustic neuroma using the transcanal transvestibular endoscopic approach
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Tao Chen, Zhenzhang Lu, Yuxiang Zhou, Duanlong Zhao, Yongtian Lu, and Qingguo Meng
- Subjects
Medicine (General) ,R5-920 - Abstract
We evaluated the outcomes of resection of small acoustic neuromas using the transcanal transvestibular endoscopic approach. Two patients with a small acoustic neuroma were treated using this approach. The sizes of the tumors were 11 × 6 mm and 12 × 10 mm. Both tumors were removed completely without residual tumor tissue, and damage to the facial nerve and cochlear nerve was avoided. No patients developed postoperative vertigo, aggravation of postoperative facial paralysis, severe pain, or permanent postoperative complications. The patients were followed up for 6 months, and none developed recurrence. Resection of small acoustic neuromas by the transcanal transvestibular endoscopic approach is a simple and safe technique that achieves excellent functional results.
- Published
- 2021
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29. Proteomic analysis of Eriocheir sinensis hemocytes in response to hypoxia stress
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Libo Hou, Lei Zhu, Xianghui Kong, Yinyue Lu, Wen Wang, Wei Gu, Li Wang, and Qingguo Meng
- Subjects
Eriocheir sinensis ,Hemocytes ,Proteome ,Hypoxia ,Aquaculture. Fisheries. Angling ,SH1-691 - Abstract
The Chinese mitten crab, Eriocheir sinensis, is an important economic aquatic product in China. Oxygen is essential for the crab, hypoxia is a natural phenomenon common in the process of aquaculture and will bring a harmful impact on the growth, development and disease outbreak of crab. To understand the effect of hypoxia on the crab, the proteome changes of E. sinensis hemocytes in the hypoxia (1.5 ± 0.5 mg/L of DO) and the normoxia groups (6.0 ± 0.5 mg/L of DO) were obtained using iTraq labeling and affinity enrichment followed by high-resolution LC-MS/MS analysis. In total, 664 differentially expressed proteins were reliably quantified (567 up-regulated and 97 down-regulated) using 1.2-fold change in expression as a physiologically significant benchmark. GO annotation, KEGG annotation, etc. were used to analysis these significantly different expression proteins. Many pathways or biological process were identified in the process of E. sinensis hemocytes response hypoxia, such as tricarboxylic acid (TCA) cycle, cell apoptosis, VEGFR/MAPK pathway, prophenoloxidase system (proPO system), phagocytosis, and so on. Ten selected genes from these different expression proteins were verified by qRT-PCR analysis. Finally, the activity of several major antioxidant enzymes (phenoloxidase (PO), superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA)) were analysis, the results showed that hypoxia stress significantly increased these enzymes activity. These study could serve as a basis to understand the relationship between E. sinensis hemocytes and hypoxia stress, and also provide reference to study hypoxia stress in other crustaceans.
- Published
- 2021
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30. Food Applications and Potential Health Benefits of Hawthorn
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Juan Zhang, Xiaoyun Chai, Fenglan Zhao, Guige Hou, and Qingguo Meng
- Subjects
nutrition ,flavonoids ,phenolic acid ,antioxidant ,anti-cardiovascular disease ,bread ,Chemical technology ,TP1-1185 - Abstract
Hawthorn (Crataegus) is a plant of the Rosaceae family and is widely grown throughout the world as one of the medicinal and edible plants, known as the “nutritious fruit” due to its richness in bioactive substances. Preparations derived from it are used in the formulation of dietary supplements, functional foods, and pharmaceutical products. Rich in amino acids, minerals, pectin, vitamin C, chlorogenic acid, epicatechol, and choline, hawthorn has a high therapeutic and health value. Many studies have shown that hawthorn has antioxidant, anti-inflammatory, anticancer, anti-cardiovascular disease, and digestive enhancing properties. This is related to its bioactive components such as polyphenols (chlorogenic acid, proanthocyanidin B2, epicatechin), flavonoids (proanthocyanidins, mucoxanthin, quercetin, rutin), and pentacyclic triterpenoids (ursolic acid, hawthornic acid, oleanolic acid), which are also its main chemical constituents. This paper briefly reviews the chemical composition, nutritional value, food applications, and the important biological and pharmacological activities of hawthorn. This will contribute to the development of functional foods or nutraceuticals from hawthorn.
- Published
- 2022
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31. Effect of Hydrate Microscopic Distribution on Acoustic Characteristics during Hydrate Dissociation: An Insight from Combined Acoustic-CT Detection Study
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Qingtao Bu, Tongju Xing, Chengfeng Li, Jinhuan Zhao, Changling Liu, Zihao Wang, Wengao Zhao, Jiale Kang, Qingguo Meng, and Gaowei Hu
- Subjects
gas hydrate ,dissociation process ,microscopic distribution ,acoustic characteristics ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 ,Oceanography ,GC1-1581 - Abstract
Geophysical detection techniques are important methods in marine gas hydrate exploration and monitoring, because the small-scale distribution of hydrates has a large impact on the wave velocity. The acoustic response characteristics of hydrate micro-distributions have strong significance for monitoring the hydrate dissociation process. In this paper, experiments simulating the hydrate dissociation process were carried out in a self-developed experimental device combining X-ray computed tomography (X-CT) scanning and ultrasonic detection, which allowed the acoustic wave characteristics and X-CT scanning results to be simultaneously obtained during the hydrate dissociation process. This study found that the hydrate dissociation stage is divided into three stages. The hydrate begins to dissociate at spots where it comes into touch with sand particles early in the dissociation process. The main factor affecting the acoustic wave velocity of hydrates in this stage is changes in the microscopic distribution of hydrate. In the middle stage, a large amount of hydrate decomposes, and the main factor affecting the acoustic wave velocity of hydrate in this stage is the change in hydrate content. In the later stage of hydrate dissociation, the hydrate distribution pattern consists mainly of the pore-filling type, and the hydrate micro-distribution at this stage is the main factor affecting the acoustic wave velocity. This study will be of great significance for understanding the microscopic control mechanism of hydrate reservoir geophysical exploration.
- Published
- 2022
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32. Experimental Study on the Distribution Characteristics of CO2 in Methane Hydrate-Bearing Sediment during CH4/CO2 Replacement
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Jianye Sun, Xiluo Hao, Chengfeng Li, Nengyou Wu, Qiang Chen, Changling Liu, Yanlong Li, Qingguo Meng, Li Huang, and Qingtao Bu
- Subjects
CH4/CO2 replacement ,gas hydrate ,distribution characteristics ,Technology - Abstract
CH4/CO2 replacement is of great significance for the exploitation of natural gas hydrate resources and CO2 storage. The feasibility of this method relies on our understanding of the CH4/CO2 replacement efficiency and mechanism. In this study, CH4/CO2 replacement experiments were carried out to study the distribution characteristics of CH4 and CO2 in hydrate-bearing sediments during and after replacement. Similar to previously reported data, our experiments also implied that the CH4/CO2 replacement process could be divided into two stages: fast reaction and slow reaction, representing CH4/CO2 replacement in the hydrate-gas interface and bidirectional CH4/CO2 diffusion caused replacement, respectively. After replacement, the CO2 content gradually decreased, and the methane content gradually increased with the increase of sediment depth. Higher replacement percentage can be achieved with higher replacement temperature and lower initial saturation of methane hydrate. Based on the calculation of CO2 consumption amounts, it was found that the replacement mainly took place in the fast reaction stage while the formation of CO2 hydrate by gaseous CO2 and water almost runs through the whole experimental process. Thus, the pore scale CH4/CO2 replacement process in sediments can be summarized in the following steps: CO2 injection, CO2 diffusing into sedimentary layer, occurrence of CH4/CO2 replacement and CO2 hydrate formation, wrapping of methane hydrate by mixed CH4-CO2 hydrate, continuous CO2 hydrate formation, and almost stagnant CH4/CO2 replacement.
- Published
- 2022
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33. Integration of Pore-Scale Visualization and an Ultrasonic Test System of Methane Hydrate-Bearing Sediments
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Qingtao Bu, Qingguo Meng, Jie Dong, Chengfeng Li, Changling Liu, Jinhuan Zhao, Zihao Wang, Wengao Zhao, Jiale Kang, and Gaowei Hu
- Subjects
gas hydrate ,X-ray computed tomography ,micro-distribution ,acoustic property ,porous media ,Technology - Abstract
The acoustic characteristics of hydrates are important parameters in geophysical hydrate exploration and hydrate resource estimation. The microscale distribution of hydrate has an important influence on the acoustic response of a hydrate-bearing reservoir. Although microscale hydrate distributions can be determined using means such as X-ray computed tomography (X-CT), it is difficult to obtain acoustic parameters for the same sample. In this study, we developed an experimental system that integrated pore-scale visualization and an ultrasonic testing system for methane-hydrate-bearing sediments. Simultaneous X-CT observation and acoustic detection could be achieved in the same hydrate sample, which provided a new method for synchronously monitoring microscale distributions during acoustic testing of natural gas hydrate samples. Hydrate formation experiments were carried out in sandy sediments, during which the acoustic characteristics of hydrate-bearing sediments were detected, while X-ray computed tomography was performed simultaneously. This study found that hydrates formed mainly at the gas–water interface in the early stage, mainly in the pore fluid in the middle stage, and came into contact with sediments in the later stage. The development of this experimental device solved the difficult problem of determining the quantitative relationship between the microscale hydrate distribution and the acoustic properties of the reservoir.
- Published
- 2022
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34. Stereoscopic Differences in the Identification, Bioactivity, and Metabolism of C-20 and C-24 Epimeric Ginseng Saponins
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Juan, Zhang, Ruolin, Zhao, Guige, Hou, Qibao, Wang, Fenglan, Zhao, Zhi, Liu, and Qingguo, Meng
- Subjects
Pharmacology ,Drug Discovery ,General Medicine - Abstract
Abstract: Ginseng, the roots and/or rhizomes of Panax spp.(Araliaceae), has been used as a popular, herbal medicine in East Asia for at least two millennia. As a functional food and health-enhancing supplement, ginseng has been shown to have a wide range of pharmacological effects on cognition and blood circulation as well as antioxidant, antitumor, and anti-fatigue effects. The main active properties of ginseng are considered to be the triterpene saponins, often referred to as ginsenosides, which are the basis for their wide-ranging of pharmacological effects. Four of these glycosides, including protopanaxadiol, protopanaxatriol, ocotillol, and oleanolic acid, are the most common saponins found in ginseng. Compared to other ginsenosides, the C-20 chimeric ginsenosides, including Rg3, Rh2, Rg2, Rh1, PF11, C-20, and C-24, as well as epimeric ocotillol-type saponins and their derivatives exhibit significant, steric differences in biological activity and metabolism. 20(R)-ginseng saponins, one class of important rare ginsenosides, have antitumor, antioxidative, antifatigue, neuroprotective and osteoclastogenesis inhibitory effects. However, 20(R)-ginsenosides are rare in natural products and are usually prepared from 20(S)-isomers through chemical differential isomerization and microbial transformation. The C20 configuration of 20(R)-ginseng saponins is usually determined by 13C NMR and X-ray single-crystal diffraction. There are regular differences in the chemical shift values of some of the carbons of the 20(S)- and 20(R)-epimers, including C-17, C-21, and C-22. Owing to their chemical structure and pharmacological and stereoselective properties, 20(R)-ginseng saponins have attracted a great deal of attention in recent years. Herein, the stereoscopic differences in the identification, bioactivity, and metabolism of C-20 and C-24 epimeric ginseng saponins are summarized.
- Published
- 2023
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35. Laboratory Study on Hydrate Production Using a Slow, Multistage Depressurization Strategy
- Author
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Yanlong Li, Chuqiao He, Nengyou Wu, Qiang Chen, Changling Liu, Zhixue Sun, Yurong Jin, and Qingguo Meng
- Subjects
Geology ,QE1-996.5 - Abstract
Optimization of the depressurization pathways plays a crucial role in avoiding potential geohazards while increasing hydrate production efficiency. In this study, methane hydrate was formed in a flexible plastic vessel and then gas production processes were conducted at constant confining pressure and constant confining temperature. The CMG-STARS simulator was applied to match the experimental gas production behavior and to derive the hydrate intrinsic dissociation constant. Secondly, fluid production behavior, pressure-temperature (P‐T) responses, and hydrate saturation evolution behaviors under different depressurization pathways were analyzed. The results show that integrated gas-water ratio (IGWR) decreases linearly with the increase in depressurizing magnitude in each step, while it rises logarithmically with the increase in the number of steps. Under the same initial average hydrate saturation and the same total pressure-drop magnitude, a slow and multistage depressurization strategy would help to increase the IGWR and avoid severe temperature drop. The pore pressure rebounds logarithmically once the gas production is suspended, and would decrease to the regular level instantaneously once the shut-in operation is ended. We speculate that the shut-in operation could barely affect the IGWR and formation P‐T response in the long-term level.
- Published
- 2021
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36. Analysis of the Mechanical Properties of the Reconstituted Hydrate-Bearing Clayey-Silt Samples from the South China Sea
- Author
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Lin Dong, Hualin Liao, Yanlong Li, Qingguo Meng, Gaowei Hu, Jintang Wang, and Nengyou Wu
- Subjects
natural gas hydrate ,mechanical properties ,triaxial shearing tests ,clayey silt ,failure mechanisms ,failure strength ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 ,Oceanography ,GC1-1581 - Abstract
Mechanical properties of hydrate-bearing sediments (HBS) are crucial for evaluating drilling- and production-induced geo-hazards. However, investigations on mechanical behaviors of clayey-silt samples containing hydrate are insufficient due to low efficiency in preparing reconstituted hydrate-bearing samples. Herein, we carried out a series of triaxial shear tests to analyze the deformation behaviors of reconstituted clayey-silt samples containing tetrahydrofuran (THF) hydrate. The sediments were taken from the Shenhu Area, northern South China Sea. The failure mechanisms during shearing are discussed based on micro-to-macro analyses. The results imply that the stress-strain curves show obvious strain-hardening under triaxial shearing, which can be divided into elastic deformation stage, transitional stage, and plastic deformation stage. Besides, the results reveal that cohesion strengthens from 0.09 MPa to 1.28 MPa when hydrate saturation increases from 15% to 60%. Moreover, calculation models are proposed to evaluate failure strengths and Young’s modulus. Establishing empirical formula based on experimental data can quickly determine the strength parameters with knowing the hydrate saturation and stress state of clayey-silt sediments containing hydrate. It is urgent in field operations and numerical simulation to use reliable empirical models.
- Published
- 2022
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37. Design, Synthesis, Bioactivity Evaluation, Crystal Structures, and In Silico Studies of New α-Amino Amide Derivatives as Potential Histone Deacetylase 6 Inhibitors
- Author
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Yangrong Xu, Hangjun Tang, Yijie Xu, Jialin Guo, Xu Zhao, Qingguo Meng, and Junhai Xiao
- Subjects
HDAC6 inhibitors ,non-hydroxamate ,α-amino amide ,synthesis ,bioactivity evaluation ,crystal structure ,Organic chemistry ,QD241-441 - Abstract
Hydroxamate, as a zinc-binding group (ZBG), prevails in the design of histone deacetylase 6(HDAC6) inhibitors due to its remarkable zinc-chelating capability. However, hydroxamate-associated genotoxicity and mutagenicity have limited the widespread application of corresponding HDAC6 inhibitors in the treatment of human diseases. To avoid such side effects, researchers are searching for novel ZBGs that may be used for the synthesis of HDAC6 inhibitors. In this study, a series of stereoisomeric compounds were designed and synthesized to discover non-hydroxamate HDAC6 inhibitors using α-amino amide as zinc-ion-chelating groups, along with a pair of enantiomeric isomers with inverted L-shaped vertical structure as cap structures. The anti-proliferative activities were determined against HL-60, Hela, and RPMI 8226 cells, and 7a and its stereoisomer 13a exhibited excellent activities against Hela cells with IC50 = 0.31 µM and IC50 = 5.19 µM, respectively. Interestingly, there is a significant difference between the two stereoisomers. Moreover, an evaluation of cytotoxicity toward human normal liver cells HL-7702 indicated its safety for normal cells. X-ray single crystal diffraction was employed to increase insights into molecule structure and activities. It was found that the carbonyl of the amide bond is on the different side from the amino and pyridine nitrogen atoms. To identify possible protein targets to clarify the mechanism of action and biological activity of 7a, a small-scale virtual screen using reverse docking for HDAC isoforms (1–10) was performed and the results showed that HDAC6 was the best receptor for 7a, suggesting that HDAC6 may be a potential target for 7a. The interaction pattern analysis showed that the α-amino amide moiety of 7a coordinated with the zinc ion of HDAC6 in a bidentate chelate manner, which is similar to the chelation pattern of hydroxamic acid. Finally, the molecular dynamics simulation approaches were used to assess the docked complex’s conformational stability. In this work, we identified 7a as a potential HDAC6 inhibitor and provide some references for the discovery of non-hydroxamic acid HDAC6 inhibitors.
- Published
- 2022
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38. Experimental Investigation into Three-Dimensional Spatial Distribution of the Fracture-Filling Hydrate by Electrical Property of Hydrate-Bearing Sediments
- Author
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Jinhuan Zhao, Changling Liu, Qiang Chen, Changchun Zou, Yang Liu, Qingtao Bu, Jiale Kang, and Qingguo Meng
- Subjects
fracture-filling hydrate ,hydrate formation process ,three-dimensional spatial distribution ,electrical property ,Technology - Abstract
As a future clean energy resource, the exploration and exploitation of natural gas hydrate are favorable for solving the energy crisis and improving environmental pollution. Detecting the spatial distribution of natural gas hydrate in the reservoir is of great importance in natural gas hydrate exploration and exploitation. Fracture-filling hydrate, one of the most common types of gas hydrate, usually appears as a massive or layered accumulation below the seafloor. This paper aims to detect the spatial distribution variation of fracture-filling hydrate in sediments using the electrical property in the laboratory. Massive hydrate and layered hydrate are formed in the electrical resistivity tomography device with a cylindrical array. Based on the electrical resistivity tomography data during the hydrate formation process, the three-dimensional resistivity images of the massive hydrate and layered hydrate are established by using finite element forward, Gauss–Newton inversion, and inverse distance weighted interpolation. Massive hydrate is easier to identify than layered hydrate because of the big difference between the massive hydrate area and surrounding sediments. The diffusion of salt ions in sediments makes the boundary of massive hydrate and layered hydrate change with hydrate formation. The average resistivity values of massive hydrate (50 Ω⋅m) and layered hydrate (1.4 Ω⋅m) differ by an order of magnitude due to the difference in the morphology of the fracture. Compared with the theoretical resistivity, it is found that the resistivity change of layered hydrate is in accordance with the change tendency of the theoretical value. The formation characteristic of massive hydrate is mainly affected by the pore water distribution and pore microstructure of hydrate. The hydrate formation does not necessarily cause the increase in resistivity, but the increase of resistivity must be due to the formation of hydrate. The decrease of resistivity in fine-grains is not obvious due to the cation adsorption of clay particles. These results provide a feasible approach to characterizing the resistivity and growth characteristics of fracture-filling hydrate reservoirs and provide support for the in-situ visual detection of fracture-filling hydrate.
- Published
- 2022
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39. Experimental Investigation of Hydrate Production via Deep Depressurization Using a Large-Scale Laboratory Reactor
- Author
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Li Huang, Jiale Kang, Qingtao Bu, Qingguo Meng, Changling Liu, and Nengyou Wu
- Subjects
Fuel Technology ,General Chemical Engineering ,Energy Engineering and Power Technology - Published
- 2023
- Full Text
- View/download PDF
40. Maximum Sizes of Fluid-Occupied Pores within Hydrate-Bearing Porous Media Composed of Different Host Particles
- Author
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Lele Liu, Nengyou Wu, Changling Liu, Qingguo Meng, Haitao Tian, Yizhao Wan, and Jianye Sun
- Subjects
Geology ,QE1-996.5 - Abstract
Hydraulic properties of hydrate-bearing sediments are largely affected by the maximum size of pores occupied by fluids. However, effects of host particle properties on the maximum size of fluid-occupied pores within hydrate-bearing sediments remain elusive, and differences in the maximum equivalent, incircle, and hydraulic diameters of fluid-occupied pores evolving with hydrate saturation have not been well understood. In this study, numerical simulations of grain-coating and pore-filling hydrate nucleation and growth within different artificial porous media are performed to quantify the maximum equivalent, incircle, and hydraulic diameters of fluid-occupied pores during hydrate formation, and how maximum diameters of fluid-occupied pores change with hydrate saturation is analyzed. Then, theoretical models of geometry factors for incircle and hydraulic diameters are proposed based on fractal theory, and variations of fluid-occupied pore shapes during hydrate formation are discussed. Results show that host particle properties have obvious effects on the intrinsic maximum diameters of fluid-occupied pores and introduce discrepancies in evolutions of the maximum pore diameters during hydrate formation. Pore-filling hydrates reduce the maximum incircle and hydraulic diameters of fluid-occupied pores much more significantly than grain-coating hydrates; however, hydrate pore habits have minor effects on the maximum equivalent diameter reduction. Shapes of fluid-occupied pores change little due to the presence of grain-coating hydrates, but pore-filling hydrates lead to much fibrous shapes of fluid-occupied pores.
- Published
- 2020
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41. In Situ Synthesis of All-Solid-State Z-Scheme BiOBr0.3I0.7/Ag/AgI Photocatalysts with Enhanced Photocatalytic Activity Under Visible Light Irradiation
- Author
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Junlin Lu, Chaoqun Shang, Qingguo Meng, Haiqin Lv, Zhihong Chen, Hua Liao, Ming Li, Yongguang Zhang, Mingliang Jin, Mingzhe Yuan, Xin Wang, and Guofu Zhou
- Subjects
Z-scheme ,Photocatalytic ,BiOBr0.3I0.7/Ag/AgI ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Abstract A series of novel visible light driven all-solid-state Z-scheme BiOBr0.3I0.7/Ag/AgI photocatalysts were synthesized by facile in situ precipitation and photo-reduction methods. Under visible light irradiation, the BiOBr0.3I0.7/Ag/AgI samples exhibited enhanced photocatalytic activity compared to BiOBr0.3I0.7 and AgI in the degradation of methyl orange (MO). The optimal ratio of added elemental Ag was 15%, which degraded 89% of MO within 20 min. The enhanced photocatalytic activity of BiOBr0.3I0.7/Ag/AgI can be ascribed to the efficient separation of photo-generated electron–hole pairs through a Z-scheme charge-carrier migration pathway, in which Ag nanoparticles act as electron mediators. The mechanism study indicated that ·O2 − and h+ are active radicals for photocatalytic degradation and that a small amount of ·OH also participates in the photocatalytic degradation process.
- Published
- 2018
- Full Text
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42. Design, Synthesis, and Antibacterial Evaluation of Novel Ocotillol Derivatives and Their Synergistic Effects with Conventional Antibiotics
- Author
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Doudou Zhang, Yucheng Cao, Kaiyi Wang, Zhuoyue Shi, Ruodong Wang, Qingguo Meng, and Yi Bi
- Subjects
ocotillol-type derivatives ,HA-MRSA ,antibiotics ,structural modification ,synergistic effects ,Organic chemistry ,QD241-441 - Abstract
The improper use of antibiotics has led to the development of bacterial resistance, resulting in fewer antibiotics for many bacterial infections. Especially, the drug resistance of hospital-acquired methicillin-resistant Staphylococcus aureus (HA-MRSA) is distinctly serious. This research designed and synthesized two series of 3-substituted ocotillol derivatives in order to improve their anti-HA-MRSA potency and synergistic antibacterial activity. Among the synthesized compounds, 20–31 showed minimum inhibitory concentration (MIC) values of 1–64 µg/mL in vitro against HA-MRSA 18–19, 18–20, and S. aureus ATCC29213. Compound 21 showed the best antibacterial activity, with an MIC of 1 μg/mL and had synergistic inhibitory effects. The fractional inhibitory concentration index (FICI) value was 0.375, when combined with chloramphenicol (CHL) or kanamycin (KAN). The structure–activity relationships (SARs) of ocotillol-type derivatives were also summarized. Compound 21 has the potential to be developed as a novel antibacterial agent or potentiator against HA-MRSA.
- Published
- 2021
- Full Text
- View/download PDF
43. What factors drive open innovation in China's public sector? A case study of official document exchange via microblogging (ODEM) in Haining.
- Author
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Nan Zhang, Xuejiao Zhao, Zhongwen Zhang, Qingguo Meng, and Haibo Tan
- Published
- 2017
- Full Text
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44. Synergistic Effects of Ag Nanoparticles/BiV1-xMoxO4 with Enhanced Photocatalytic Activity
- Author
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Mengting Yu, Shixiong Zhou, Qingguo Meng, Haiqin Lv, Zhihong Chen, Yongguang Zhang, Mingliang Jin, Mingzhe Yuan, Xin Wang, and Guofu Zhou
- Subjects
Hydrothermal synthesis ,Photocatalytic ,Metal doping ,Ag/BiV1-xMoxO4 ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Abstract In recent years, BiVO4 has drawn much attention as a novel photocatalyst given its excellent ability to absorb visible light. This work reports the development of Ag-modified BiV1-xMoxO4 composites through a facile hydrothermal synthesis with the subsequent photoinduced reduction of Ag+ at almost neutral pH conditions. Metallic Ag nanoparticles were deposited on the (040) facet of Mo-doped BiVO4 powders. The crystal structure and morphology of the as-prepared samples were studied by XRD and SEM analyses. Moreover, the photocatalytic performance of BiVO4, Ag/BiVO4, and Ag-modified BiV1-xMoxO4 were evaluated by the degradation of rhodamine B (RhB). The Ag/BiV0.9925Mo0.0075O4 composite exhibited the most efficient photocatalytic performance. The present work provides greater insight into the application of BiVO4 in the field of photocatalysis.
- Published
- 2017
- Full Text
- View/download PDF
45. Discovery, semisynthesis, biological activities, and metabolism of ocotillol-type saponins
- Author
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Juan Liu, Yangrong Xu, Jingjing Yang, Wenzhi Wang, Jianqiang Zhang, Renmei Zhang, and Qingguo Meng
- Subjects
biological activity ,discovery ,metabolism ,ocotillol-type saponin ,semisynthesis ,Botany ,QK1-989 - Abstract
Ocotillol-type saponins are one kind of tetracyclic triterpenoids, sharing a tetrahydrofuran ring. Natural ocotillol-type saponins have been discovered in Panax quinquefolius L., Panax japonicus, Hana mina, and Vietnamese ginseng. In recent years, the semisynthesis of 20(S/R)-ocotillol-type saponins has been reported. The biological activities of ocotillol-type saponins include neuroprotective effect, antimyocardial ischemia, antiinflammatory, antibacterial, and antitumor activities. Owing to their chemical structure, pharmacological actions, and the stereoselective activity on antimyocardial ischemia, ocotillol-type saponins are subjected to extensive consideration. In this review, we sum up the discovery, semisynthesis, biological activities, and metabolism of ocotillol-type saponins.
- Published
- 2017
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46. In Situ Hydrothermal Construction of Direct Solid-State Nano-Z-Scheme BiVO4/Pyridine-Doped g‑C3N4 Photocatalyst with Efficient Visible-Light-Induced Photocatalytic Degradation of Phenol and Dyes
- Author
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Qingguo Meng, Haiqin Lv, Mingzhe Yuan, Zhen Chen, Zhihong Chen, and Xin Wang
- Subjects
Chemistry ,QD1-999 - Published
- 2017
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47. Modulation of photocatalytic activity of SrBi2Ta2O9 nanosheets in NO removal by tuning facets exposure
- Author
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Nan Li, Qiuhui Zhu, Guimei Liu, Qi Zhao, Haiqin Lv, Mingzhe Yuan, Qingguo Meng, Yingtang Zhou, Jingkun Xu, and Chuanyi Wang
- Subjects
Polymers and Plastics ,Mechanics of Materials ,Mechanical Engineering ,Materials Chemistry ,Metals and Alloys ,Ceramics and Composites - Published
- 2022
- Full Text
- View/download PDF
48. Spiroplasma eriocheiris Invasion Into Macrobrachium rosenbergii Hemocytes Is Mediated by Pathogen Enolase and Host Lipopolysaccharide and β-1, 3-Glucan Binding Protein
- Author
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Mingxiao Ning, Yunji Xiu, Meijun Yuan, Jingxiu Bi, Libo Hou, Wei Gu, Wen Wang, and Qingguo Meng
- Subjects
Macrobrachium rosenbergii ,Spiroplasma eriocheiris ,interactive proteins ,innate immunity ,infection ,Immunologic diseases. Allergy ,RC581-607 - Abstract
Spiroplasma eriocheiris is a crustacean pathogen, without a cell wall, that causes enormous economic loss. Macrobrachium rosenbergii hemocytes are the major targets during S. eriocheiris infection. As wall-less bacteria, S. eriocheiris, its membrane protein should interact with host membrane protein directly and firstly when invaded in host cell. In this investigation, six potential hemocyte receptor proteins were identified firstly that mediate interaction between S. eriocheiris and M. rosenbergii. Among these proteins, lipopolysaccharide and β-1, 3-glucan binding protein (MrLGBP) demonstrated to bind to S. eriocheiris using bacterial binding assays and confocal microscopy. Four spiroplasma ligand proteins for MrLGBP were isolated and identified. But, competitive assessment demonstrated that only enolase of S. eriocheiris (SeEnolase) could be a candidate ligand for MrLGBP. Subsequently, the interaction between MrLGBP and SeEnolase was confirmed by co-immunoprecipitation and co-localization in vitro. After the interaction between MrLGBP and SeEnolase was inhibited by antibody neutralization test, the virulence ability of S. eriocheiris was effectively reduced. The quantity of S. eriocheiris decreased in Drosophila S2 cells after overexpression of MrLGBP, compared with the controls. In addition, RNA interference (RNAi) knockdown of MrLGBP made M. rosenbergii more sensitive to S. eriocheiris infection. Further studies found that the immune genes, including MrLGBP and prophenoloxidase (MrproPO), MrRab7A, and Mrintegrin α1 were significantly up-regulated by SeEnolase stimulation. After SeEnolase pre-stimulation, the ability of M. rosenbergii resistance to S. eriocheiris was significantly improved. Collectively, this investigation demonstrated that MrLGBP and pathogen SeEnolase involved in mediating S. eriocheiris invasion into M. rosenbergii hemocytes.
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- 2019
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49. Modified Nanopillar Arrays for Highly Stable and Efficient Photoelectrochemical Water Splitting
- Author
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Lanyan Huang, Qingguo Meng, Chaoqun Shang, Mingliang Jin, Lingling Shui, Yongguang Zhang, Zhang Zhang, Zhihong Chen, Mingzhe Yuan, Xin Wang, Krzysztof Kempa, and Guofu Zhou
- Subjects
graphitic carbon nitride ,hydrogen evolution ,photoelectrochemistry ,quantum dots ,TiO2 nanopillars ,Technology ,Environmental sciences ,GE1-350 - Abstract
Abstract Atomically modified graphitic carbon nitride quantum dots (QDs), characterized by strongly increased reactivity and stability, are developed. These are deposited on arrays of TiO2 nanopillars used as a photoanode for the photoelectrochemical water splitting. This photoanode shows excellent stability, with 111 h of continuous work without any performance loss, which outperforms the best‐reported results by a factor of 10. Remarkably, our photoanode produces hydrogen even at zero bias. The excellent performance is attributed to the enhancement of photoabsorption, as well as to the promotion of charge separation between TiO2 nanopillars and the QDs.
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- 2019
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50. Assessment of left ventricular energy loss in patients with mild coronary artery stenosis by using vector flow mapping combined with exercise stress echocardiography
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Qiuyu Xiao, Xin Zhao, Rui Yang, Zizhuo Li, Dongmei Li, Yuanyuan Xie, Xinyue Mao, Yi Wang, Lixue Yin, Chunmei Li, Mingliang Zuo, Qingguo Meng, Wenhua Li, Xuebing Liu, Zhaohuan Li, Qingfeng Zhang, and Yan Deng
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Radiology, Nuclear Medicine and imaging ,Cardiology and Cardiovascular Medicine - Published
- 2023
- Full Text
- View/download PDF
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