Ionic Size Effect on the Double Layer Properties: A Modified Poisson-Boltzmann Theory

Ping Lou,Jin Yong Lee 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.9

On the basis of a simple modified Poisson-Boltzmann (SMPB) theory, taking into account the finite ionic size, the analytic expression for the effect of ionic size on the diffuse layer potential drop at negative charge densities has been given for the simple 1:1 electrolyte. It is shown that the potential drop across the diffuse layer depends on the size of the ions in the electrolyte. For a given electrolyte concentration and electrode charge density, the diffuse layer potential drop in a small ion system is smaller than that in a large ion system. It is also displayed that the diffuse layer potential drop is always less than the value of the Gouy-Chapman (GC) theory, and the deviation increases as the electrode charge density increases for a given electrolyte concentration. These theoretical results are consistent with the results of the Monte-Carlo simulation [Fawcett and Smagala, Electrochimica Acta 53, 5136 (2008)], which indicates the importance of including steric effects in modeling diffuse layer properties.

Band Structures of Narrow Zigzag Silicon Carbon Nanoribbons

Lou, Ping,Lee, Jin Yong American Chemical Society 2009 The Journal of Physical Chemistry Part C Vol.113 No.29

Exact Analytic Result of Contact Value for the Density in a Modified Poisson−Boltzmann Theory of an Electrical Double Layer

Lou, Ping,Lee, Jin Yong American Chemical Society 2009 Journal of chemical theory and computation Vol.5 No.4

Unusual Non-magnetic Metallic State in Narrow Silicon Carbon Nanoribbons by Electron or Hole Doping

Ping Lou,이진용 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.3

We investigated the width (N) dependence on the magnetization of N-ZSiC NR with electron and hole doping on the basis of systematic DFT calculations. The critical values of the upper and down critical concentration to give the maximum and zero magnetic moment at edge Si/C atoms by electron/hole doping (xup,e, xdown,e, xup,h, and xdown,h) depend on the width of N-ZSiC NR. Moreover, due to xup,e ≠ xup,h and xdown,e ≠ xdown,h, the electron and hole doping effect are asymmetry, i.e, the critical electron doping value (xdown,e) is smaller than the critical hole doping value (xdown,h) and is almost independent of the width of NZSiC NR though the other critical values of the electron and hole doping that influence the magnetization of N-ZSiC NR depend on the width. It was also found that at xdown,e or xdown,h doping, the N-ZSiC NR turns into unusual non-magnetic metallic state. The magnetic behavior was discussed based on the band structures and projected density of states (PDOS) under the effect of electron/hole doping.

Unusual Non-magnetic Metallic State in Narrow Silicon Carbon Nanoribbons by Electron or Hole Doping

Lou, Ping,Lee, Jin-Yong Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.3

We investigated the width (N) dependence on the magnetization of N-ZSiC NR with electron and hole doping on the basis of systematic DFT calculations. The critical values of the upper and down critical concentration to give the maximum and zero magnetic moment at edge Si/C atoms by electron/hole doping ($x_{up,e}$, $x_{down,e}$, $x_{up,h}$, and $x_{down,h}$) depend on the width of N-ZSiC NR. Moreover, due to $x_{up,e}\;{\neq}\;x_{up,h}$ and $x_{down,e}\;{\neq}\;x_{down,h}$, the electron and hole doping effect are asymmetry, i.e, the critical electron doping value ($x_{down,e}$) is smaller than the critical hole doping value ($x_{down,h}$) and is almost independent of the width of NZSiC NR though the other critical values of the electron and hole doping that influence the magnetization of N-ZSiC NR depend on the width. It was also found that at $x_{down,e}$ or $x_{down,h}$ doping, the N-ZSiC NR turns into unusual non-magnetic metallic state. The magnetic behavior was discussed based on the band structures and projected density of states (PDOS) under the effect of electron/hole doping.

Ionic Size Effect on the Double Layer Properties: A Modified Poisson-Boltzmann Theory

Lou, Ping,Lee, Jin-Yong Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.9

On the basis of a simple modified Poisson-Boltzmann (SMPB) theory, taking into account the finite ionic size, the analytic expression for the effect of ionic size on the diffuse layer potential drop at negative charge densities has been given for the simple 1:1 electrolyte. It is shown that the potential drop across the diffuse layer depends on the size of the ions in the electrolyte. For a given electrolyte concentration and electrode charge density, the diffuse layer potential drop in a small ion system is smaller than that in a large ion system. It is also displayed that the diffuse layer potential drop is always less than the value of the Gouy-Chapman (GC) theory, and the deviation increases as the electrode charge density increases for a given electrolyte concentration. These theoretical results are consistent with the results of the Monte-Carlo simulation [Fawcett and Smagala, Electrochimica Acta 53, 5136 (2008)], which indicates the importance of including steric effects in modeling diffuse layer properties.

Random vibration analysis of train-slab track-bridge coupling system under earthquakes

Zhi-ping Zeng,Xian-feng He,Yan-gang Zhao,Zhi-wu Yu,Ling-kun Chen,Wen-tao Xu,Ping Lou 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.5

This study aimed to investigate the random vibration characteristic of train-slab track-bridge interaction system subjected to both track irregularities and earthquakes by use of pseudo-excitation method (PEM). Each vehicle subsystem was modeled by multibody dynamics. A three-dimensional rail-slabgirder-pier finite element model was created to simulate slab track and bridge subsystem. The equations of motion for the entire system were established based on the constraint condition of no jump between wheel and rail. The random load vectors of equations of motion were formulated by transforming track irregularities and seismic accelerations into a series of deterministic pseudo-excitations according to their respective power spectral density (PSD) functions by means of PEM. The time-dependent PSDs of random vibration responses of the system were obtained by step-by-step integration method, and the corresponding extreme values were estimated based on the first-passage failure criterion. As a case study, an ICE3 high-speed train passing a fifteen-span simply supported girder bridge simultaneously excited by track irregularities and earthquakes is presented. The evaluated extreme values and the PSD characteristic of the random vibration responses of bridge and train are analyzed, and the influences of train speed and track irregularities (without earthquakes) on the random vibration characteristic of bridge and train are discussed.

Endovascular Treatment for Iliac Vein Compression Syndrome: a Comparison between the Presence and Absence of Secondary Thrombosis

Wen-Sheng Lou,Jian-Ping Gu,Xu He,Liang Chen,Hao-Bo Su,Guo-Ping Chen,Jing-Hua Song,Tao Wang 대한영상의학회 2009 Korean Journal of Radiology Vol.10 No.2

Objective: To evaluate the value of early identification and endovascular treatment of iliac vein compression syndrome (IVCS), with or without deep vein thrombosis (DVT). Materials and Methods: Three groups of patients, IVCS without DVT (group 1, n = 39), IVCS with fresh thrombosis (group 2, n = 52) and IVCS with non-fresh thrombosis (group 3, n = 34) were detected by Doppler ultrasonography, magnetic resonance venography, computed tomography or venography. The fresh venous thrombosis were treated by aspiration and thrombectomy, whereas the iliac vein compression per se were treated with a self-expandable stent. In cases with fresh thrombus, the inferior vena cava filter was inserted before the thrombosis suction, mechanical thrombus ablation, percutaneous transluminal angioplasty, stenting or transcatheter thrombolysis. Results: Stenting was performed in 111 patients (38 of 39 group 1 patients and 73 of 86 group 2 or 3 patients). The stenting was tried in one of group 1 and in three of group 2 or 3 patients only to fail. The initial patency rates were 95% (group 1), 89% (group 2) and 65% (group 3), respectively and were significantly different (p = 0.001). Further, the six month patency rates were 93% (group 1), 83% (group 2) and 50% (group 3), respectively, and were similarly significantly different (p = 0.001). Both the initial and six month patency rates in the IVCS patients (without thrombosis or with fresh thrombosis), were significantly greater than the patency rates of IVCS patients with non-fresh thrombosis. Conclusion: From the cases examined, the study suggests that endovascular treatment of IVCS, with or without thrombosis, is effective. Objective: To evaluate the value of early identification and endovascular treatment of iliac vein compression syndrome (IVCS), with or without deep vein thrombosis (DVT). Materials and Methods: Three groups of patients, IVCS without DVT (group 1, n = 39), IVCS with fresh thrombosis (group 2, n = 52) and IVCS with non-fresh thrombosis (group 3, n = 34) were detected by Doppler ultrasonography, magnetic resonance venography, computed tomography or venography. The fresh venous thrombosis were treated by aspiration and thrombectomy, whereas the iliac vein compression per se were treated with a self-expandable stent. In cases with fresh thrombus, the inferior vena cava filter was inserted before the thrombosis suction, mechanical thrombus ablation, percutaneous transluminal angioplasty, stenting or transcatheter thrombolysis. Results: Stenting was performed in 111 patients (38 of 39 group 1 patients and 73 of 86 group 2 or 3 patients). The stenting was tried in one of group 1 and in three of group 2 or 3 patients only to fail. The initial patency rates were 95% (group 1), 89% (group 2) and 65% (group 3), respectively and were significantly different (p = 0.001). Further, the six month patency rates were 93% (group 1), 83% (group 2) and 50% (group 3), respectively, and were similarly significantly different (p = 0.001). Both the initial and six month patency rates in the IVCS patients (without thrombosis or with fresh thrombosis), were significantly greater than the patency rates of IVCS patients with non-fresh thrombosis. Conclusion: From the cases examined, the study suggests that endovascular treatment of IVCS, with or without thrombosis, is effective.

Stability analysis of deepwater compliant vertical access riser about parametric excitation

Lou, Min,Hu, Ping,Qi, Xiaoliang,Li, Hongwei The Society of Naval Architects of Korea 2019 International Journal of Naval Architecture and Oc Vol.11 No.2

If heave motion in the platform causes horizontal parametric vibration of a Compliant Vertical Access Riser (CVAR), the riser may become unstable. A combination of riser parameters lies in the unstable region aggravates vibrational damage to the riser. Change of axial tensile stress in the riser combined with its natural frequency and mode shape change results in mode coupling. In accordance with the state transition matrices of the riser in the coupled and uncoupled states, the stable and unstable regions were obtained by Floquet theory, and the vibration response under different conditions was obtained. The parametric excitation of the CVAR is shown to occur mainly in first-order unstable regions. Mode coupling may cause parametric excitation in the least stable regions. Damping reduces the extent of unstable regions to a certain extent.

Asymmetric Reduction of Ethyl Acetoacetate Catalyzed by Immobilized Acetobacter sp. CCTCC M209061 Cells in Hydrophilic Ionic Liquid Hybrid System

Ping Wei,Pei Xu,Xiao-Ting Wang,Wen-Yong Lou,Min-Hua Zong 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.2

The asymmetric reduction of ethyl acetoacetate (EAA) to ethyl (R)-3-hydroxybutyrate [(R)-EHB] using immobilized Acetobacter sp. CCTCC M209061 cells was successfully conducted in a hydrophilic ionic liquid (IL)- containing system. The best one of all the tested watermiscible ILs was 1-(hydroxyethyl)-3-methylimidazolium hydrochloride (C2OHMIM·Cl). In C2OHMIM·Cl-aqueous buffer hybrid system, it was found that the optimal IL concentration, substrate and co-substrate concentration, reaction temperature, buffer pH and shaking rate were 0.5mol/L, 45 mmol/L, 80 mmol/L, 35oC, pH 5.5 and 200 rpm, respectively. Under the optimized reaction conditions, the initial reaction rate, the yield and the product e.e. reached 4.90 μmol/min, 95.3 and > 99.0%, respectively, which were much higher than the corresponding values reported previously. The efficient biocatalytic process mediated by the immobilized cells was feasible on 500 mL preparative scale, and the biocatalysts showed good operational stability and could be recycled for at least 10 batches.