Improvement of 1,3-propanediol Oxidoreductase (DhaT) Stability Against 3-hydroxypropionaldehyde by Substitution of Cysteine Residues

Zhengbin Li,노수문,Balaji Sundara Sekar,설은희,Suman Lama,이선구,Guangyi Wang,박성훈 한국생물공학회 2016 Biotechnology and Bioprocess Engineering Vol.21 No.6

1,3-propanediol oxidoreductase (DhaT), which catalyzes the conversion of 3-hydroxypropionaldehyde (3- HPA) to 1,3-propanediol (1,3-PD) with the oxidation of NADH to NAD+, is a key enzyme in the production of 1,3- PD from glycerol. DhaT is known to be severely inactivated by its physiological substrate, 3-HPA, due to the reaction of 3-HPA with the thiol group of the cysteine residues. In this study, using site-directed mutagenesis, four cysteine residues in Klebsiella pneumoniae J2B DhaT were substituted to alanine, the amino acid commonly found in cysteine’s positions in other DhaT, individually and in combination. Among the total of 15 mutants developed, a double mutant (C28A_C107A) and a triple mutant (C28A_C93A_C107A) exhibited approximately 50 and 16% higher activity than the wild-type counterpart, respectively, after 1 h incubation with 10 mM 3-HPA. According to detailed kinetic studies, the double mutant had slightly better kinetic properties (Vmax, Kcat, and Km for both 3-HPA and NADH) than wild-type DhaT. This study shows that DhaT stability against 3-HPA can be increased by cysteine-residue removal, albeit to a limited extent.

The activation mechanism of Cu(II) to ilmenite and subsequent flotation response to a-hydroxyoctyl phosphinic acid

Fangxu Li,Hong Zhong,Shuai Wang,Guangyi Liu 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.37 No.-

In order to get close-packed hydrophobic molecular monolayer, surface modification of ilmenite wascarried out with cupric ions. As it was found by zeta potential and XPS measurement, the cupric ionsmodification occurs via ion exchange, metal hydroxides adsorption, and redox processes. Aftermodifying by cupric ions, ilmenite surface properties became more active and the adsorption amount ofa-hydroxyoctyl phosphinic acid (HPA) increased. As expected, the flotation behaviour of ilmeniteimproved. XPS measurements verified the ability to establish a covalently attached HPA on the surfacesof ilmenite after Cu(II) activation. The findings of this study will provide a fundamental basis forstrengthening flotation.

농촌인구 유출에 따른 농촌 지역 유형화와 특성 분석: 중국 연룡도 지역을 사례로

김광익(Guangyi Jin),이은하(Yinhe Li) 대한지리학회 2020 대한지리학회지 Vol.55 No.1

연변조선족자치주는 지난 40년간 중국의 개혁개방정책에 힘입어 괄목할 만한 성장을 이룩했다. 특히 연길시를 핵심으로 용정시와 도문시 등 3개 도시를 포함한 연룡도 지역은 동북아 두만강 지역 개발의 전략적 중심과 길림성 동부지역의 중심으로 건설하는 것을 목표로 세웠다. 하지만 조선족의 대규모 인구이동으로 연변지역 전체인구의 상대적 비중 뿐만아니라 중국 내 조선족 인구의 절대 규모에서도 급속한 감소 추세를 보여주고 있다. 이에 본 연구는 연룡도 지역을 중심으로 조선족 인구의 감소로 인한 농촌 지역을 유형화하고 그 특성을 분석하였다. 연룡도 지역 169개 행정촌을 연구지역으로 현지조사와 GIS분석을 통해 인구요인과 자연요인을 추출하여 농촌 지역을 인구급감형, 도농복합형, 전업농가형 등 3가지 유형으로 구분하였고 유형별 특성을 규명하였다. Yanbian autonomous prefecture has achieved rapid economic growth over the past 40 years since China’s reform and opening-up policies. In particular, the Yan-Long-Tu region, which includes three cities of Yanji, Longjing and Tumen, was set up as the strategic center of the development of Northeast Asian Tumen River, as well as the center of eastern area of Jilin Province. However, the population of Korean Chinese group has showed big decline through migration, due to a large labor migration to South Korea. This article presents types of rural areas and analyses its characteristics as the result of population outflow. We take 169 villages in Yan-Long-Tu area as research areas, extracting population and natural factors through field investigation and GIS analysis. Finally, the areas were divided into three types of rural areas including Population sharp decline type, Urban rural mixed type, Full-time farm household type, with their characteristics identified.

MTPA Trajectory Tracking Control with On‑line MRAS Parameter Identifcation for an IPMSM

Ningzhi Jin,Guangyi Li,Kai Zhou,Jinfeng Liu,Herbert Ho‑Ching Iu 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.6

The maximum torque per ampere (MTPA) control is capable of obtaining its maximal ratio of torque to current in a control system of interior permanent magnet synchronous motor (IPMSM). However, when its electrical parameters change with the actual operating conditions, the resulting MTPA trajectory will defect from the optimal one. To solve this problem, a modifed model reference adaptive system (MRAS) method is investigated for the parameter identifcation of the rotor fux linkage and the stator q-axis inductance, after a tradeof between the MTPA trajectory derivation degree with parameter change and the rank-defciency problem in the identifcation model. In this method, a full-rank estimator and its gain matrix are designed according to the Popov Hyper Stability Theorem. And the current operating point is updated using the identifed parameters in order for the real-time tracking of MTPA trajectory. Simulation and experimental results verify that the proposed method enhances remarkably the MTPA tracking control efect and the system’s torque-current characteristics for an IPMSM.

Robotic cholecystectomy versus laparoscopic cholecystectomy

Nam Hyun Baek,GuangYi Li,Keesang Yoo,Ji Hun Kim,Wook Hwan Kim 한국간담췌외과학회 2013 한국간담췌외과학회 학술대회지 Vol.2013 No.4

Characterization of Hydrogen Production by Engineered Escherichia coli Strains Using Rich Defined Media

Juanita Mathews,Quanzi Li,Guangyi Wang 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.4

Fermentation conditions (e.g., pressure and medium) are well-documented to impact the yield of microbial products in bioreactors. In this study we used carefully controlled batch fermentations to characterize hydrogen production from engineered strains of Escherichia coli and developed a rapid method of inducing hydrogen production in previously aerobically grown cells by using a rich defined medium. Our results indicated that rich defined media activated hydrogen production from aerobic pre-cultures with no lag time and yielded more hydrogen and biomass than the commonly used minimal media. Under these conditions, deletion of both uptake hydrogenase 1 (ΔhyaAB) and hydrogenase 2 (ΔhybABC) was shown to increase hydrogen yield from glucose by 10% over the wildtype strain BW25113. However, the deletion of the repressor for the formate-hydrogen-lyase (FHL-1) complex (ΔhycA) did not further increase hydrogen production. Additional deletion of lactate dehydrogenase (ldhA) and fumarate reductase (frdBC) of the mixed-acid fermentation pathway increased hydrogen yield by 22 and 23%, respectively. Interestingly, combined elimination of ldhA and frdBC in the uptake and hycA null strain increased hydrogen yield from 1.37 to 1.82 mol/mol glucose, obtaining 91% of the theoretical maximum hydrogen yield. Our results indicated the advantage of using rich defined media for inducing hydrogen production. This study represents the first report of characterizing metabolically engineered E. coli strains in batch hydrogen fermentation using rich defined media under tightly controlled conditions.

Anatomical Variation of the Glissonean Pedicle of the Right Liver

Weiguang Xu,Hee Jung Wang,Bong-Wan Kim,Yong-Keun Park,Guangyi Li 한국간담췌외과학회 2011 한국간담췌외과학회지 Vol.15 No.2

Purpose: Many studies have been conducted to date regarding whether the right hepatic vein is the accurate border that divides the anterior and posterior section of the right liver. It has been reported that the Glisson pedicle of the right liver may be an anatomical variation that does not have a consistent morphology. We analyzed the relationship between the true borders of the anterior and posterior sections, and the right hepatic vein, based on cadaver dissection and MD-CT image analysis of the anatomical variation of the Glisson pedicle of the right liver. Methods: Sixteen cadaver livers were available for dissection from the Department of Anatomy, and pre-operative MD-CTs of 20 donor livers who underwent living donor liver transplantation prior to December 2009, were obtained. We analyzed the 3D-relationship between the branches of the Glisson pedicles and the right hepatic vein of the right liver. They were divided into 3 groups according to the sliding pattern of the branches of the Glisson pedicle origin. When all segmental branches of the anterior pedicle arise from the main trunk of the anterior pedicle and all branches of posterior pedicle arise from the main trunk of posterior pedicle, it was designated as Group A (Normal Group). When a portion of the segmental branches of the anterior pedicle arises from the main trunk of the posterior pedicle, it was designated as Group B (Posterior dominant group). When a portion of the branches of the posterior pedicle arises from the main trunk of the anterior pedicle, it was designated as Group C (Anterior dominant group). Results: Among the 16 cadaver liver dissections, 6 cases were in Group A, 5 in Group B, and 3 in Group C. Two cases were excluded from the study because the inferior right hepatic vein was the main draining vein of the right liver. The analysis of preoperative MD-CT of the 20 donor livers showed that there were 13, 4, and 3 patients in Groups A, B, and C, respectively. Conclusion: According to Couinaud"s theory of anatomy, the right hepatic vein serves as the border between the anterior and posterior sections of the right liver. But, due to the frequent anatomical variations, an adequate understanding of the anatomical variations of the right Glisson pedicle should be necessary for liver surgery.

Bone Grafting Can Promote the Prognosis of Displaced Femoral Neck Fractures: A Follow-up of the Clinical Significance of Bone Defects

Xiaozhong Zhu,Wei Wang,Zhiyuan Wang,Yi Zhu,Guangyi Li,Jiong Mei 대한정형외과학회 2023 Clinics in Orthopedic Surgery Vol.15 No.4

Background: Femoral neck fractures (FNFs) comprise a large proportion of osteoporotic fractures in Asia. However, the full range of prognostic variables that affect prognosis remains unclear. Here, we aimed to determine whether the severity of bone defects at the fracture site and other variables impact the prognosis of displaced FNFs. Methods: We evaluated the incidence of FNF internal fixation failures at regular intervals after surgery in data collected retrospectively. Digital Imaging and Communications in Medicine (DICOM) magnetic resonance imaging data of the displaced FNFs of 204 patients (> 20 years old; mean age, 52.3 years; men, 55.4%) who underwent internal fixation were used to construct threedimensional (3D) virtual models of the femoral neck region. We calculated the position and volume of bone defect (VBD) using our independently developed algorithm and Mimics software. Each participant was followed up for at least 24 months; complications were noted and correlated with VBD and demographic and clinical variables. Results: On the basis of VBD values calculated from virtual reduction models, 57 patients were categorized as having a mild defect, 100 as having a moderate defect, and 47 as having a severe defect. Age (p = 0.046) and VBD (p < 0.001) were significantly correlated with internal fixation failure. Multivariate analysis revealed that severe bone defects were associated with internal fixation failure (adjusted odds ratio [aOR], 23.073; 95% confidence interval [CI], 2.791–190.732) and complications (aOR, 8.945; 95% CI, 1.829–43.749). In patients with a severe defect, bone grafting was inversely associated with internal fixation failure (aOR, 0.022; 95% CI, 0.002–0.268) and complications (aOR, 0.023; 95% CI, 0.002–0.299). Conclusions: Bone defect severity was associated with internal fixation failure and other complications. For young adults with large VBDs, bone grafting of the defect can reduce the risk of internal fixation failure. These results provide useful new quantitative information for precisely classifying displaced FNFs and guiding subsequent optimal treatments.