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Modal parameter estimation of civil structures based on improved variational mode decomposition
Lun-hai Zhi,Feng Hu,Chunfeng Zhao,Jingfeng Wang 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.79 No.6
This paper proposes an improved variational mode decomposition (IVMD) algorithm for structural modal parameter estimation based on non-stationary responses. In this improved VMD, the mean envelope entropy (MEE) and particle swarm optimization (PSO) are first employed to determine the optimal decomposition parameters for the subsequent VMD analysis. Then the VMD algorithm is used to decompose the non-stationary data into a number of intrinsic mode functions (IMFs). After obtaining the IMFs based on the IVMD, structural modal parameters such as natural frequencies and damping ratios of civil structures can be determined by using Natural Excitation Technique (NExT) and Direct Interpolating approach (DI). The feasibility and accuracy of the proposed procedure are evaluated by both numerical and full-scale examples. The natural frequencies and damping ratios are successfully identified from the vibration responses with high noise and nonstationary characteristics. The results of this study illustrate that the proposed procedure provides a powerful approach to identify the modal parameters of civil structures using non-stationary responses.
( Zhao Lian ),( Ing Bo Jiang ),( Shuang Chi ),( Guo Hua Guan ),( Ying Li ),( Ji Lun Li ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.12
β-1,3-glucanosyltransferases play essential roles in cell wall biosynthesis in yeast. Kluyveromyces lactis has six putative β-1,3-glucanosyltransferase genes. KlGAS1-1 and KlGAS1-2 are homologs of Saccharomyces cerevisiae gene GAS1. RT-qPCR indicated the transcription level of KlGAS1-1 was significantly reduced while heterologous protein (thermostable xylanase B) secretion was enhanced during medium optimization. To evaluate if these two events were related, and to improve xylanase B secretion in K. lactis, we constructed KlGAS1-1 and KlGAS1-2 single deletion strains and double deletion strain, respectively. KlGAS1-1 gene deletion resulted in the highest xylanase B activity among the three mutants. Only the double deletion strain showed morphology similar to that of the GAS1 deletion mutant in S. cerevisiae. The two single deletion strains differed in terms of cell wall thickness and xylanase B secretion. Transcription levels of β-1,3-glucanosyltransferase genes and genes related to protein secretion and transport were assayed. The β-1,3-glucanosyltransferase genes displayed transcription complementation in the cell wall synthesis process. KlGAS1-1 and KlGAS1-2 affected transcription levels of secretion- and transport-related genes. Differences in protein secretion ratio among the three deletion strains were associated with changes of transcription levels of secretion- and transport-related genes. Our findings indicate that KlGAS1-1 deletion is an effective tool for enhancing industrial-scale heterologous protein secretion in K. lactis.
Comparison of Microbial Diversity and Composition in the Jejunum and Colon of Alcohol-Dependent Rats
( Yang Fan ),( Zhao Ya-e ),( Wei Ji-dong ),( Lu Yu-fan ),( Zhang Ying ),( Sun Ya-lun ),( Ma Meng-yu ),( Zhang Rui-ling ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.11
Alcohol dependence is a global public health problem, yet the mechanisms of alcohol dependence are incompletely understood. The traditional view has been that ethanol alters various neurotransmitters and their receptors in the brain and causes the addiction. However, an increasing amount of experimental evidence suggests that gut microbiota also influence brain functions via gut-to-brain interactions, and may therefore induce the development of alcohol use disorders. In this study, a rat model of alcohol dependence and withdrawal was employed, the gut microbiota composition was analyzed by high-throughput 16S rRNA gene sequencing, and the metagenome function was predicted by PICRUSt software. The results suggested that chronic alcohol consumption did not significantly alter the diversity and richness of gut microbiota in the jejunum and colon, but rather markedly changed the microbiota composition structure in the colon. The phyla Bacteroidetes and eight genera including Bacteroidales S24-7, Ruminococcaceae, Parabacteroides, Butyricimonas, et al were drastically increased, however the genus Lactobacillus and gauvreauii in the colon were significantly decreased in the alcohol dependence group compared with the withdrawal and control groups. The microbial functional prediction analysis revealed that the proportions of amino acid metabolism, polyketide sugar unit biosynthesis and peroxisome were significantly increased in the AD group. This study demonstrated that chronic alcohol consumption has a dramatic effect on the microbiota composition structure in the colon but few effects on the jejunum. Inducement of colonic microbiota dysbiosis due to alcohol abuse seems to be a factor of alcohol dependence, which suggests that modulating colonic microbiota composition might be a potentially new target for treating alcohol addiction.
Ziqiang Zhang,Lun Wang,Jinnong Liao,Jing Zhao,Qi Yang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.8
The rigid-flexible coupling structure of creatures with jumping ability has the advantages of high stiffness and good flexibility, which are of great significance to its research. However, existing research on jumping robots has not demonstrated the effect of multiflexibility links on the jumping performance. In this paper, a Watt-type one degree-of-freedom six-bar mechanism is regarded as research object. For a jumping leg including multiple flexible links and a flexible joint with a floating frame, a rigid-flexible coupling dynamic model is established with a pseudo-rigid-body model being used. On this basis, the effect of structural and installation parameters on the jumping performance is analyzed. Results show that different flexible links have distinct effects on the jumping performance, and properly reducing the stiffness of flexible links can improve the jumping performance. The results of this study provide a design basis for jumping robots with a rigid-flexible coupling structure.
Foamy oil properties and horizontal well inflow performance relationship under solution gas drive
Congge He,Zifei Fan,Anzhu Xu,Lun Zhao 한국자원공학회 2019 Geosystem engineering Vol.22 No.3
In this study, we modified the foamy oil fluid property model by defining the coalescence rate constant to account for the fraction of entrained gas in the oil phase. The modified model was verified by matching the calculated results with experimental data. Then, the horizontal well inflow performance of foamy heavy oil reservoirs was calculated by incorporating the modified fluid properties into the horizontal well flow rate equation at pseudo-steady state. In addition, the horizontal well inflow performance of foamy oil under solution gas drive and the corresponding conventional oil was compared. The results show that the foamy oil fluid properties calculated by the modified fluid property model are consistent with the experimental results, thus verifying the correctness of the model. Comparing the horizontal well inflow performance of foamy oil and conventional oil, it shows that when the average reservoir pressure is between bubble point pressure and pseudo-bubble point pressure, the flow rate of foamy oil is higher than that of the conventional oil. When the average reservoir pressure drops below the pseudo-bubble point pressure, the flow rate of foamy oil is close to that of the conventional oil. Foamy efficiency, defined as the ratio of the difference between the flow rate of foamy oil and conventional oil to the conventional oil flow rate, has the biggest value, about 15%, close to the pseudo-bubble point.
miR-27a as an Oncogenic microRNA of Hepatitis B Virus-related Hepatocellular Carcinoma
Wu, Xin-Jun,Li, Yan,Liu, Dong,Zhao, Lun-De,Bai, Bin,Xue, Ming-Hui Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.2
microRNAs (miRNAs) are small non-coding RNAs that regulate gene expression through post-transcriptional interactions with mRNA. miRNAs have recently emerged as key regulators of various cancers. Although miR-27a has been implicated in several other cancers, its role in hepatitis B virus-related hepatocellular carcinoma (HCC) is unknown. In this study, we showed miR-27a to be frequently up-regulated in HCC tissues and HCC cell lines (HepG2 and Huh7). Overexpression of miR-27a enhanced cell proliferation, promoted migration and invasion, and activated cell cycling in HepG2 and Huh7 cells. In summary, our results suggest that up-regulation of miR-27a may play an oncogenic role in the development of HCC and might thus be a new therapeutic target in HCC patients.
Sun, Jie,Xiong, Ju,Zhen, Yan,Chen, Zhao-Lun,Zhang, Hua Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.11
Objective: To explore the correlation of human papillomavious (HPV) infection with expression of p53 and proliferating cell nuclear antigen (PCNA) in patients with different ethnicity in Xinjiang, China. Methods: 166 biopsy specimens from 83 laryngeal squamous cell carcinomas (LSCC), 63 laryngeal papillomas (LP), and 20 laryngeal inflammatory polyps (LIP) were included in this study. HPV infection was determined by polymerase chain reaction (PCR) using specific types of HPV primers. Expression of p53 and PCNA was assessed using immunohistostaining. Results: The frequency of HPV 6/11 was higher in LP (33.3%) than in LSCC (9.6%) (P<0.0005), whereas the frequency of HPV 16/18 was higher in LSCC (37.3 %) than in LP (6.3%) (P<0.0005). Patients of the Han ethnic group with LSCC had a higher infection rate with HPV 6/11 or HPV 6/11 and HPV 16/18 coinfection than those of Uygur and Kazak ethnicity (P<0.05). Overexpression of p53 and PCNA were higher in LSCC (62.7%, 57.8%) than in LP (38%, 33.3%) (P<0.005, and P<0.005, respectively). That of p53 was not associated with lymph-node metastases and clinical stages, but overexpression of PCNA closely correlated with clinical stage. Conclusions: These results strongly implicate HPV6/11 infection in the carcinogenesis of LSCC and LP, respectively. There was a higher coincidence of increased malignancy of laryngeal tumors with overexpression of p53 and PCNA. Overexpression of p53 may serve as an early risk marker for malignant transformation in HPV infected cells while the overexpression of PCNA may serve as a late marker for progression of LSCC.
Zhang Pei-Pei,Liang Su-Xia,Wang Hua-Lun,Yang Kun,Nie Shao-Chen,Zhang Tong-Mei,Tian Yuan-Yuan,Xu Zhao-Yuan,Chen Wei,Yan Ying-Bin 한국통합생물학회 2021 Animal cells and systems Vol.25 No.5
The aim of this study was to compare the functional characteristics of mesenchymal stromal cells (MSCs) from a sheep model of traumatic temporomandibular joint (TMJ) fibrous and bony ankylosis. A sheep model of bilateral TMJ trauma-induced fibrous ankylosis on one side and bony ankylosis on the contralateral side was used. MSCs from fibrous ankylosed callus (FAMSCs) or bony ankylosed callus (BA-MSCs) at weeks 1, 2, 4, and 8 after surgery were isolated and cultured. MSCs derived from the bone marrow of the mandibular condyle (BM-MSCs) were used as controls. The MSCs from the different sources were characterized morphologically, phenotypically, and functionally. Adherence and trilineage differentiation potential were presented in the ovine MSCs. These cell populations highly positively expressed MSC-associated specific markers, namely CD29, CD44, and CD166, but lacked CD31 and CD45 expressions. The BA-MSCs had higher clonogenic and proliferative potentials than the FA-MSCs. The BA-MSCs also showed higher osteogenic and chondrogenic potentials, but lower adipogenic capacity than the FA-MSCs. In addition, the BA-MSCs demonstrated higher chondrogenic, but lower osteogenic capacity than the BM-MSCs. Our study suggests that inhibition of the osteogenic and chondrogenic differentiations of MSCs might be a promising strategy for preventing bony ankylosis in the future.