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( Liangliang Wang ),( Jiajun Wang ),( Hao Shi ),( Huaxiang Gu ),( Yu Zhang ),( Xun Li ),( Fei Wang ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.6
Glycerol dehydrogenases (GlyDHs) are essential for glycerol metabolism in vivo, catalyzing its reversible reduction to 1,3-dihydroxypropranone (DHA). The gldA gene encoding a putative GlyDH was cloned from Thermoanaerobacterium thermosaccharolyticum DSM 571 (TtGlyDH) and expressed in Escherichia coli. The presence of Mn(2+) enhanced its enzymatic activity by 79.5%. Three highly conserved residues (Asp(171), His(254), and His(271)) in TtGlyDH were associated with metal ion binding. Based on an investigation of glycerol oxidation and DHA reduction, TtGlyDH showed maximum activity towards glycerol at 60°C and pH 8.0 and towards DHA at 60°C and pH 6.0. DHA reduction was the dominant reaction, with a lower Km(DHA) of 1.08 ± 0.13 mM and Vmax of 0.0053 ± 0.0001 mM/s, compared with glycerol oxidation, with a Km(glycerol) of 30.29 ± 3.42 mM and Vmax of 0.042 ± 0.002 mM/s. TtGlyDH had an apparent activation energy of 312.94 kJ/mol. The recombinant TtGlyDH was thermostable, maintaining 65% of its activity after a 2-h incubation at 60°C. Molecular modeling and site-directed mutagenesis analyses demonstrated that TtGlyDH had an atypical dinucleotide binding motif (GGG motif) and a basic residue Arg(43), both related to dinucleotide binding.
Electric field effect on the Raman scattering of a hydrogenic impurity in spherical quantum dot
Liangliang Lu,Wenfang Xie,Shijun Liang 한국물리학회 2011 Current Applied Physics Vol.11 No.6
Using the perturbation method and the effective mass approximation, we studied the combined effects of impurity and external electric field on Raman scattering in a spherical quantum dot with a parabolic potential. Based on the computed energies and wave functions, the differential cross-section involved in this process is investigated, and the selection rules are also calculated. Our results suggest that the scattering intensity is strongly affected by the impurity and external electric field considered in this work.
Fabrication of Columnar NaNbO3‑Based Particles Through Topochemical Microcrystal Conversion
Liangliang Liu,Rui Lv,Zhuangzhuang Guo,Yongqiang Wang 대한금속·재료학회 2020 ELECTRONIC MATERIALS LETTERS Vol.16 No.1
The columnar NaNbO3-based particles with a perovskite structure were successfully synthesized through topochemical microcrystal conversion. First, the precursor was fabricated by facile MSS in the Nb2O5–KCl system. A good dispersion and high aspect ratio were satisfed simultaneously with a small amount of SrCO3 and KSr2Nb5O15 (KSN) seed. Then, columnar NaNbO3-based particles, 10 μm in length and 1 μm in diameter, were obtained via the simple molten salt reaction from the precursor. The results of NaNbO3-based ceramics suggested that the as-synthesized NaNbO3-based particles had the good mechanical properties and homogeneous chemical composition.
Liangliang Xu,Lian Li,Peng Wang,Ming Zhang,Yanfang Zhang,Xiangyong Hao,Lvnan Yan,Bo Li,Tianfu Wen,Mingqing Xu 거트앤리버 소화기연관학회협의회 2019 Gut and Liver Vol.13 No.6
Background/Aims: Microvascular invasion (MVI) is an established risk factor for hepatocellular carcinoma (HCC). However, prediction models that specifically focus on the individual prognoses of HCC patients with MVI is lacking. Methods: A total of 385 HCC patients with MVI were randomly assigned to training and validation cohorts in a 2:1 ratio. The outcomes were disease-free survival (DFS) and overall survival (OS). Prognostic nomograms were established based on the results of multivariate analyses. The concordance index (C-index), calibration plots and Kaplan-Meier curves were employed to evaluate the accuracy, calibration and discriminatory ability of the models. Results: The independent risk factors for both DFS and OS included age, tumor size, tumor number, the presence of gross vascular invasion, and the presence of Glisson’s capsule invasion. The platelet-tolymphocyte ratio was another risk factor for OS. On the basis of these predictors, two nomograms for DFS and OS were constructed. The C-index values of the nomograms for DFS and OS were 0.712 (95% confidence interval [CI], 0.679 to 0.745; p<0.001) and 0.698 (95% CI, 0.657 to 0.739; p<0.001), respectively, in the training cohort and 0.704 (95% CI, 0.650 to 0.708; p<0.001) and 0.673 (95% CI, 0.607 to 0.739; p<0.001), respectively, in the validation cohort. The calibration curves showed optimal agreement between the predicted and observed survival rates. The Kaplan-Meier curves suggested that these two nomograms had satisfactory discriminatory abilities. Conclusions: These novel predictive models have satisfactory accuracy and discriminatory abilities in predicting the prognosis of HCC patients with MVI after hepatectomy.
Enhancing Water Solubility of High-Molecule-Weight Lignin through Sulfomethylation
Liangliang An,Yong Sik Kim 한국산림바이오에너지학회 2019 산림바이오에너지 Vol.29 No.2
The water solubility and charge density of high-molecule-weight lignin were enhanced through sulfomethylation. Acetone lignin which is the high-molecule-weight fraction extracted from kraft lignin was reacted with CH₂O to and Na₂SO₃ to introduce sulfonic acid groups into lignin macromolecule. Gel permeation chromatography (GPC), Fourier-transform infrared spectroscopy(FT-IR), elemental analysis, and sulfonic acid group content analysis were performed to confirm the successful sulfomethylation of lignin. The thermal property, electrochemical property, and water solubility were further discussed. The results showed the highest content of sulfonic acid groups in sulfomethylated lignin is up to 1.481 mmol/g and its sulfur content is 1.9%. The number-average molecular weight was increased from 1850 g·mol<SUP>-1</SUP> to 2110 g·mol<SUP>-1</SUP> as a result of the introduction of sulfomethyl groups which was confirmed by the analyses of FT-IR. Although the thermal stability decreased slightly, the water solubility was increased from 6.5% to 49% and charge density was increased from 0.10 meq/ g to 4.81 meq/ g, which indicated the high-molecule-weight lignin is promising as a dispersant and plasticizer in concrete preparation.
Influence of oil pipe corrosion defects on the sealing performance of annular BOP
Liangliang Dong,Yuan Tang,Liuyang Wang 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.84 No.3
Due to corrosion defects on the surface of the oil pipe, the sealing performance of the annular blowout preventer (BOP) decreases, and the leakage of toxic and harmful gases such as H2S and SO2 will threaten the safety of operators on the well. Therefore, this paper establishes the FE model for evaluating the sealing performance of BOP-oil pipe corrosion defects, which is based on the rubber large deformation theory and rubber core sealing mechanism, and designs the experiment of BOP sealing performance to verify the accuracy of the FE model. The sealing performance of BOP sealing oil pipe with corrosion defects is studied. The research results show that the sealing performance of BOP is more sensitive to the axial size of corrosion defects. With the increase of oil pipe outer diameter, the critical size of defects increases continuously. The sensitivity of radial and depth dimensions is low, When for 88.9 mm outer diameter oil pipe, the axial critical size of corrosion defect is 20 mm, the radial critical size is 16 mm and the critical depth is 2 mm. Fit the formula between the outer diameter of oil pipe and the piston increment. According to the formula, the operator can calculate the piston stroke increment required by the BOP to complete the sealing when the oil pipe is corroded.