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Prediction of Natural Frequency of Free Spanning Subsea Pipelines
Zhi-Gang Xiao,Xiao-Ling Zhao 한국강구조학회 2010 International Journal of Steel Structures Vol.10 No.1
Free spans or suspended spans normally occur in subsea pipelines due to the irregularity of seabed and/or the scouring action of sea water. A problem of significance to the free spans of subsea pipeline is that currents or waves flowing across pipelines can shed vortices and induce vibration which may cause fatigue damage to the pipelines. Natural frequencies of free spans are required when solving vibration amplitude and cyclic stresses in the free span. The natural frequency is usually calculated with simplified equations, where factors such as boundary conditions and axial forces are not accurately taken into account. In this study, the influence of boundary conditions, mass of hydrocarbon products, axial force, and multiple spans on the natural frequencies of pipeline are investigated and corresponding suggestions are provided for frequency calculation.
An Overview of Remote Sensing of Chlorophyll Fluorescence
Xiao-Gang Xing,Dong-Zhi Zhao,Yu-Guang Liu,Jian-Hong Yang,Peng Xiu,Lin Wang 한국해양과학기술원 2007 Ocean science journal Vol.42 No.1
Besides empirical algorithms with the blue-green ratio, the algorithms based on fluorescence are also important and valid methods for retrieving chlorophyll-a concentration in the ocean waters, especially for Case II waters and the sea with algal blooming. This study reviews the history of initial cognitions, investigations and detailed approaches towards chlorophyll fluorescence, and then introduces the biological mechanism of fluorescence remote sensing and main spectral characteristics such as the positive correlation between fluorescence and chlorophyll concentration, the red shift phenomena. Meanwhile, there exist many influence factors that increase complexity of fluorescence remote sensing, such as fluorescence quantum yield, physiological status of various algae, substances with related optical property in the ocean, atmospheric absorption etc. Based on these cognitions, scientists have found two ways to calculate the amount of fluorescence detected by ocean color sensors: fluorescence line height and reflectance ratio. These two ways are currently the foundation for retrieval of chlorophyll-a concentration in the ocean. As the in-situ measurements and synchronous satellite data are continuously being accumulated, the fluorescence remote sensing of chlorophyll-a concentration in Case II waters should be recognized more thoroughly and new algorithms could be expected.
Molecular cloning of two novel stearoyl-acyl desaturase genes from winterness wheat
Zhi-Fu Guo,Feng-Zhen Li,Xiao-Gang Ma,Feng Lin,Hui Ma,Li-Jing Chen,Ming Zhong,Li-Ping Bai,Ying Yi 한국유전학회 2011 Genes & Genomics Vol.33 No.5
Using RT-PCR and rapid amplification of cDNA ends, two new full-length cDNAs of SAD (TaSAD1 and TaSAD2) were obtained from a hardiest winter wheat cultivar (Mironovskaya808). Sequence comparison analysis showed that the deduced amino acid sequences of TaSAD1 and TaSAD2 had high similarity to those of other reported SAD proteins. They were also different each other by some substitutions, insertions and/or deletions involving single amino acid residues or motifs. Based on evolution analysis, it was clear that all SAD genes from Poaceae were closer than those from other genus such as Arabidopsis,Glycine, Triadica, Brassica, Sesamum and Bassia. All SAD genes clustered into two major groups in Poaceae. Meanwhile,TaSAD1 and TaSAD2 were clustered into different groups. The tertiary structure prediction indicated that both TaSAD1 and TaSAD2 proteins were a compact globular protein and their model structures almost were the same.
Gang Wang,Peng-yu Duan,Yuan Ma,Xi-na Li,Feng-zhi Qu,Liang Ji,Xiao-yu Guo,Wang-jun Zhang,Fan Xiao,Le Li,Ji-sheng Hu,Bei Sun 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-
Currently, preliminary results have confirmed the existence of receptor-interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain-like protein (MLKL)-dependent necroptosis of pancreatic acinar cells during early acute pancreatitis (AP), which might be a potential target for the effective regulation of necroinflammatory injury. However, the exact effect of receptor-interacting protein kinase 1 (RIPK1)-dependent regulated acinar cell necrosis on AP is still uncertain. In our study, we first explored the changes in the degree of local and systemic inflammation in AP rats when the activation of acinar cell RIPK1 was inhibited. The RIPK1 inhibitor Nec-1 was used to treat rats, and the levels of related inflammatory markers, necrosis indicators and apoptotic indicators were measured. Changes in pancreatic nuclear factor κB (NF-κB) and aquaporin 8 (AQP8) expression were noted. Next, the expression of AQP8 in AR42J cells was inhibited, and the degree of cell necrosis and inflammatory damage was found to be significantly reduced. Most importantly, we demonstrated that the RIPK1/NF-ĸB/AQP8 axis might be a potential regulatory pathway mediating RIPK1-dependent regulated acinar cell necrosis in early AP. Finally, we used the NF-κB inhibitor PDTC and Nec-1 to treat rats in different groups and measured the degree of pathological pancreatic injury, the activation of RIPK1, and the expression of NF-κB and AQP8. In summary, we hypothesized that there might be a RIPK1/NF-ĸB/AQP8 pathway controlling RIPK1-dependent regulated necrosis of acinar cells in AP, which might be a promising therapeutic target against AP-related injury.
Convenient Synthesis of N-Methylpyrrolidine-2-thione and Some Thioamides
Zong, Zhi-Min,Peng, Yao-Li,Liu, Zhi-Gang,Zhou, Shi-Lu,Wu, Lin,Wang, Xiao-Hua,Wei, Xian-Yong,Lee, Chul Wee 한국화학공학회 2003 Korean Journal of Chemical Engineering Vol.20 No.2
The synthesis of thioamides and thiolactams, which are used as important organic intermediates, has attracted great attention. However, expensive reagents, severe reaction conditions and low yields of the target products made conventional methods inconvenient and economically infeasible. To overcome these disadvantages, we investigated a new process for synthesizing thioamides and thiolactams. We examine thermal reactions of CS_2 with N-methyl-2-pyrrolidinones, formylamide, acetamide and N, N-dimethylformylamide, respectively. The results show that under optimum conditions N-methylpyttolidine-2-thione and the corresponding thioamides can be obtained in good to excellent yields by the above thionation reactions.
Expression and Clinical Significance of miRNA-34a in Colorectal Cancer
Ma, Zhi-Bin,Kong, Xiao-Lin,Cui, Gang,Ren, Cui-Cui,Zhang, Ying-Jie,Fan, Sheng-Jin,Li, Ying-Hua Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.21
Background: The aim of this study was to investigate differences of miRNA-34a expression in benign and malignant colorectal lesions. Materials and Methods: Samples of cancer, paraneoplastic tissues and polyps were selected and total RNA was extracted by conventional methods for real-time PCR to detect the miRNA-34a expression. In addition, the LOVO colorectal cancer cell line was cultured, treated with the demethylating agent 5-azacytidine and screened for differentially expressed miRNA-34a. Results: After the drug treatment, the miRNA-34a expression of colorectal cancer cell line LOVO was increased and real-time PCR showed that levels of expression in both cell line and colorectal cancer tissues were low, as compared to paraneoplastic tissue (p<0.05). Polyps tissues had significantly higher expression than paraneoplastic and colorectal cancer samples (p<0.05). Conclusions: miRNA-34a-5p may play a role as a tumor suppressor gene in colorectal cancer, with involvement of DNA methylation.
Metabolic engineering of Escherichia coli for the production of putrescine: A four carbon diamine
Qian, Zhi-Gang,Xia, Xiao-Xia,Lee, Sang Yup Wiley Subscription Services, Inc., A Wiley Company 2009 Biotechnology and bioengineering Vol.104 No.4
<P>A four carbon linear chain diamine, putrescine (1,4-diaminobutane), is an important platform chemical having a wide range of applications in chemical industry. Biotechnological production of putrescine from renewable feedstock is a promising alternative to the chemical synthesis that originates from non-renewable petroleum. Here we report development of a metabolically engineered strain of Escherichia coli that produces putrescine at high titer in glucose mineral salts medium. First, a base strain was constructed by inactivating the putrescine degradation and utilization pathways, and deleting the ornithine carbamoyltransferase chain I gene argI to make more precursors available for putrescine synthesis. Next, ornithine decarboxylase, which converts ornithine to putrescine, was amplified by a combination of plasmid-based and chromosome-based overexpression of the coding genes under the strong tac or trc promoter. Furthermore, the ornithine biosynthetic genes (argC-E) were overexpressed from the trc promoter, which replaced the native promoter in the genome, to increase the ornithine pool. Finally, strain performance was further improved by the deletion of the stress responsive RNA polymerase sigma factor RpoS, a well-known global transcription regulator that controls the expression of ca. 10% of the E. coli genes. The final engineered E. coli strain was able to produce 1.68 g L<SUP>−1</SUP> of putrescine with a yield of 0.168 g g<SUP>−1</SUP> glucose. Furthermore, high cell density cultivation allowed production of 24.2 g L<SUP>−1</SUP> of putrescine with a productivity of 0.75 g L<SUP>−1</SUP> h<SUP>−1</SUP>. The strategy reported here should be useful for the bio-based production of putrescine from renewable resources, and also for the development of strains capable of producing other diamines, which are important as nitrogen-containing platform chemicals. Biotechnol. Bioeng. 2009; 104: 651–662 © 2009 Wiley Periodicals, Inc.</P>