Efficacy and Safety of Endoscopic Resection Therapies for Rectal Carcinoid Tumors: A Meta-Analysis

Lei He,Tao Deng,He-Sheng Luo 연세대학교의과대학 2015 Yonsei medical journal Vol.56 No.1

Purpose: Several endoscopic resection therapies have been applied for the treatment of rectal carcinoid tumors. However, there is currently no consensus regarding the optimal strategy. We performed a meta-analysis to compare the efficacy and safety of endoscopic mucosal resection (EMR) or modified EMR (m-EMR) versus endoscopicsubmucosal dissection (ESD) for the treatment of rectal carcinoid tumors. Materials and Methods: PubMed, Web of Science, Medline, Embase and CNKI were searched up to the end of January 2014 in order to identify all studies on the effectsof EMR (or m-EMR) and ESD on rectal carcinoid tumors. Results: A total of fourteen studies involving 782 patients were included. The pooled data suggested a significantly higher rate of pathological complete resection among patients treated with ESD or m-EMR than those treated with EMR [odds ratio (OR)=0.42, 95% confidenceinterval (CI): 0.25‒0.71; OR=0.10, 95% CI: 0.03‒0.33, respectively], while there was no significant difference between the m-EMR group and ESD group (OR=1.19, 95% CI: 0.49‒2.86); The procedure time of ESD was longer than EMR or m-EMR groups [mean differences (MD)=-11.29, 95% CI: -14.19 ‒ -8.38, MD= -10.90, 95% CI: -18.69 ‒ -3.11, respectively], but it was insignificance between the EMR and m-EMR groups. No significant differences were detected among the treatmentgroups with regard to complications or recurrence. Conclusion: The results of this meta-analysis suggest that treatment of rectal carcinoid tumors with ESD or m-EMR is superior to EMR, and the efficacy of m-EMR is equivalence to ESD treatment. However, more well-designed studies are needed to confirm these findings.

Numerical simulation of unsteady propeller/rudder interaction

Lei He,Spyros A. Kinnas 대한조선학회 2017 International Journal of Naval Architecture and Oc Vol.9 No.6

A numerical approach based on a potential flow method is developed to simulate the unsteady interaction between propeller and rudder. In this approach, a panel method is used to solve the flow around the rudder and a vortex lattice method is used to solve the flow around the propeller, respectively. An iterative procedure is adopted to solve the interaction between propeller and rudder. The effects of one component on the other are evaluated by using induced velocities due to the other component at every time step. A fully unsteady wake alignment algorithm is implemented into the vortex lattice method to simulate the unsteady propeller flow. The Rosenhead-Moore core model is employed during the wake alignment procedure to avoid the singularities and instability. The Lamb-Oseen vortex model is adopted in the present method to decay the vortex strength around the rudder and to eliminate unrealistically high induced velocity. The present methods are applied to predict the performance of a cavitating horn-type rudder in the presence of a 6-bladed propeller. The predicted cavity patterns compare well with those observed from the experiments.

Numerical simulation of unsteady propeller/rudder interaction

He, Lei,Kinnas, Spyros A. The Society of Naval Architects of Korea 2017 International Journal of Naval Architecture and Oc Vol.9 No.6

A numerical approach based on a potential flow method is developed to simulate the unsteady interaction between propeller and rudder. In this approach, a panel method is used to solve the flow around the rudder and a vortex lattice method is used to solve the flow around the propeller, respectively. An iterative procedure is adopted to solve the interaction between propeller and rudder. The effects of one component on the other are evaluated by using induced velocities due to the other component at every time step. A fully unsteady wake alignment algorithm is implemented into the vortex lattice method to simulate the unsteady propeller flow. The Rosenhead-Moore core model is employed during the wake alignment procedure to avoid the singularities and instability. The Lamb-Oseen vortex model is adopted in the present method to decay the vortex strength around the rudder and to eliminate unrealistically high induced velocity. The present methods are applied to predict the performance of a cavitating horn-type rudder in the presence of a 6-bladed propeller. The predicted cavity patterns compare well with those observed from the experiments.

A novel recyclable nano-adsorbent for enhanced oil recovery with efficient removal of Ca2+ and Cr6+ from oilfield wastewater

Lei He,Yong Dai,Zhe Wang,Lutao Yang,Luxia Zhang,Pengpeng Hu,Yutian Lei,Hong Mo,Haomiao Zhu,Jun Zhang 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.8

Oilfield wastewater has a significantly negative influence on the recovery efficiency due to its hypersalinity. Therefore, magnetic graphene oxide (GO) modified with ethylene diamine tetraacetic acid (EDTA) and grafted bypolyethylene glycol (PEG) nano-adsorbent was prepared to remove the Ca2+ and Cr6+ in Jidong Oilfield wastewaterspecifically. It was noteworthy that PEG-g-EDTA/Fe3O4/GO nano-adsorbent had excellent adsorption performance,with removal ratios up to 71.6% for Ca2+ and 42.7% for Cr6+ at 30 min. After the fifth recycling run, the nano-adsorbentstill remained with high removal ratios (69.3% for Ca2+ and 30.5% for Cr6+) and high reuse rates (89.4% for Ca2+and 95.2% for Cr6+), indicating that the nano-adsorbent had outstanding adsorption-desorption efficacy and high reusability. The adsorption test results demonstrated that the total salinity of the treated oilfield wastewater decreased byabout 5,000 ppm, and the displacement efficiency further increased by 12.5% by chemical flooding compared with theuntreated wastewater. Therefore, PEG-g-EDTA/Fe3O4/GO nano-adsorbent is an adsorbent with excellent potentialwhich can effectively remove Ca2+ and Cr6+ in oilfield wastewater to enhance oil recovery (EOR).

Microvessel Density as a Prognostic Factor in Ovarian Cancer: a Systematic Review and Meta-analysis

He, Lei,Wang, Qiao,Zhao, Xia Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.3

Background: The prognostic value of microvessel density (MVD), reflecting angiogenesis, detected in ovarian cancer is currently controversial. Here we performed a meta-analysis of all relevant eligible studies. Materials and Methods: A comprehensive search of online PubMed, Medline, EMBASE and Sciencedirect was performed to identify all related articles. The search strategy was designed as 'microvessel density', 'ovarian cancer', 'ovarian neoplasm', 'CD34' and 'angiogenesis'. Results: The studies were categorized by author/year, number of patients, FIGO stage, histology, cutoff value for microvessel density, types of survival analysis, methods of hazard rations (HR) estimation, HR and its 95% confidence interval (CI). Combined hazard ratios suggested that high MVD was associated with poor overall survival (OS) and progression-free survival (PFS), with HR and 95% CIs of 1.84 (1.33-2.35) and 1.36 (1.06-1.66), respectively. Subgroup analysis showed that high MVD detected by CD34 was relevant for OS [HR=1.67 (1.36-2.35)], but not MVD detected with other antibodies [HR=2.11 (0.90-3.31)]. Another subgroup analysis indicated that high MVD in patients without pre-chemotherapy, but not with pre-chemotherapy, was associated with OS [HR=1.88(1.59-2.18 and HR=1.70 (-0.18-3.59)]. Conclusions: The OS and PFS with high MVD were significant poorer than with low MVD in ovarian cancer patients. However, high MVD detected by CD34 seems to be more associated with survival for patients without pre-chemotherapy.

A Discrete State-Space Control Scheme for Dynamic Voltage Restorers

He Lei,Xin-Chun Lin,Ming-Yu Xue,Yong Kang 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.3

This paper presents a discrete state-space controller using state feedback control and feed-forward decoupling to provide a desirable control bandwidth and control stability for dynamic voltage restorers (DVR). The paper initially discusses three typical applications of a DVR. The load-side capacitor DVR topology is preferred because of its better filtering capability. The proposed DVR controller offers almost full controllability because of the multi-feedback of state variables, including one-beat delay feedback. Feed-forward decoupling is usually employed to prevent disturbances of the load current and source voltage. Directly obtaining the feed-forward paths of the load current and source voltage in the discrete domain is a complicated process. Fortunately, the full feed-forward decoupling strategy can be easily applied to the discrete state-space controller by means of continuous transformation. Simulation and experimental results from a digital signal processor-based system are included to support theoretical analysis.

Research on Paralleled Three-Phase Four-Leg Voltage Source Inverters Based on Dual-Loop Control in αβο Coordinate

He Lei,Lanling Fei,Jian Xiong,Xinchun Lin,Yong Kang 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

This paper presents a dual-loop control scheme in αβο coordinates for paralleled three-phase four-leg voltage source inverters. Using α-β-ο coordinate, output voltages of the inverter can be controlled in each channel (αβο) independently as the voltage component in relating to the inductor in the fourth leg only exists in o-channel. The use of interleaving for paralleled three-phase four-leg inverter would contribute to harmonic cancellation. For control loop, a proportional-resonant regulator in the outer loop and a proportional regulator in the inner loop are incorporated. Meanwhile a state observer for estimating the output voltage and inductor current in each channel is introduced to compensate one time-step delay of the system. The performance of proposed control scheme is verified by experimental results.

DNM3OS Facilitates Ovarian Cancer Progression by Regulating miR-193a-3p/MAP3K3 Axis

Lei He,Guolin He 연세대학교의과대학 2021 Yonsei medical journal Vol.62 No.6

Purpose: Long non-coding RNAs (lncRNAs) are essential regulators in the development of ovarian cancer (OC). Nonetheless, thefunction of lncRNA DNM3 opposite strand/antisense RNA (DNM3OS) in OC remains unclear. This work aimed to investigate thebiological roles and underlying mechanisms of DNM3OS in OC. Materials and Methods: Quantitative real-time polymerase chain reaction was conducted to examine DNM3OS, microRNA(miR)-193a-3p, and mitogen-activated protein kinase 3 (MAP3K3) mRNA expression in OC tissues and cell lines. Kaplan-Meiersurvival analysis was employed to analyze the relationship between DNM3OS expression and the prognosis of OC patients. Cellcounting kit-8, 5-ethynyl-2'-deoxyuridine, and transwell experiments were conducted to monitor cell proliferation, migration,and invasion, respectively. Western blot was applied to examine epithelial-mesenchymal transition associated protein (E-cadherinand N-cadherin) expression. Luciferase reporter gene and RNA immunoprecipitation experiments were performed to confirmthe relationships among DNM3OS, miR-193a-3p, and MAP3K3. Pearson’s correlation analysis was adopted to analyze thecorrelations among DNM3OS, miR-193a-3p, and MAP3K3 mRNA. Results: DNM3OS expression was remarkably increased in OC tissues and cell lines, which was associated with the unfavorableprognosis of the patients. DNM3OS overexpression enhanced OC cell proliferation, migration, and invasion; suppressed E-cadherinprotein expression; and facilitated N-cadherin protein expression, while the transfection of miR-193a-3p mimics had the oppositeeffects. DNM3OS directly interacted with miR-193a-3p, and miR-193a-3p targeted MAP3K3 by directly binding to 3'UTR. DNM3OS could up-regulate the expression of MAP3K3 via repressing miR-193a-3p expression. Conclusion: DNM3OS, as an oncogenic lncRNA, increases the malignancy of OC cells via regulation of an miR-193a-3p/MAP3K3 axis.

A Discrete State-Space Control Scheme for Dynamic Voltage Restorers

Lei, He,Lin, Xin-Chun,Xue, Ming-Yu,Kang, Yong The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.3

This paper presents a discrete state-space controller using state feedback control and feed-forward decoupling to provide a desirable control bandwidth and control stability for dynamic voltage restorers (DVR). The paper initially discusses three typical applications of a DVR. The load-side capacitor DVR topology is preferred because of its better filtering capability. The proposed DVR controller offers almost full controllability because of the multi-feedback of state variables, including one-beat delay feedback. Feed-forward decoupling is usually employed to prevent disturbances of the load current and source voltage. Directly obtaining the feed-forward paths of the load current and source voltage in the discrete domain is a complicated process. Fortunately, the full feed-forward decoupling strategy can be easily applied to the discrete state-space controller by means of continuous transformation. Simulation and experimental results from a digital signal processor-based system are included to support theoretical analysis.

Pole-to-Ground Fault Analysis for MMC-HVDC Grid

Zhen He,Jiabing Hu,Lei Lin,Zhiyuan He 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Pole-to-ground (PTG) fault analysis is of vital importance for HVDC grid. However, many factors are not considered in the existing studies, such as the asymmetrical property of PTG fault, the coupling issue between dc transmission lines and the complexity of dc grid’s structure. This paper presents a PTG fault analysis method, which is based on common- and differential-mode (CDM) transformation. Similar to the symmetrical component method in ac system, the transformation decomposes the HVDC grid into CDM networks at first. Then, under the perspective of CDM components, a transfer impedance based analysis is performed to obtain the analytical expressions of PTG fault characteristics. The proposed PTG fault analysis method is applicable to arbitrary HVDC grid topologies. And the analytical expressions can give theoretical guidance for fault protection. The validity of the proposed PTG fault analysis method is verified by comparison with the simulation results in PSCAD/EMTDC.