Preparation and electrochemical properties of mesoporous Co3O4 crater-like microspheres as supercapacitor electrode materials

Lu Wang,Xiaoheng Liu,Xin Wang,Xujie Yang,Lude Lu 한국물리학회 2010 Current Applied Physics Vol.10 No.6

Mesoporous Co3O4 microspheres with unique crater-like morphology were obtained by utilizing the mesoporous silica material MCM-41 as a template. The analysis results of N2 adsorptionedesorption measurement indicate that the product has a large BrunauereEmmetteTeller (BET) surface area of 60 m2 g-1 and a narrow pore size distribution centering around 3.7 nm. Its electrochemical properties were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS)measurements. The findings reveal that this novel morphology material has a smaller inner resistance of about 0.4 U and a higher onset frequency of 550 Hz. This material can provide a high specific capacitance of 102 F g-1 and a large capacity retention of 74% in 500 continuous cycles test at a sweep rate of 3 mV s-1. More significantly, the mass loading of electroactive species can reach as large as 2 mg cm-2, which is one order of magnitude larger than common amount used.

Drag reduction characterizations of turbulent channel flow with surfactant additive by proper orthogonal decomposition and wavelet transform

Lu Wang,Zhiying Zheng,Weihua Cai,Fengchen Li 한국유변학회 2020 Korea-Australia rheology journal Vol.32 No.1

To explore the drag-reducing characteristics of turbulent channel flows with surfactant additive at relatively high Reynolds number from the perspectives of energy spectrum and multi-scale resolution, the two-dimensional fluctuation velocity fields of turbulent channel flows with/without surfactant additive at Reynolds number of Re = 590 obtained by large eddy simulation are decomposed by two-dimensional proper orthogonal decomposition (POD) and wavelet transform (WT). POD results show that the low-order eigenmode occupying most energy can be used to capture large-scale vortex structures, and fewer eigenmodes can be employed to capture coherent structures (CSs) in surfactant solution case compared with that in the Newtonian fluid. The spatial structures depicted by POD eigenmode state that buffer layer has a tendency to move towards the center of the channel in surfactant solution. Through wavelet analysis of fluctuation velocity fields in the streamwise-wall-normal planes, it is found that CSs mainly distribute in the near-wall region and the amount of CSs is smaller in surfactant solution. The results of local Reynolds shear measure (LRM) show that local contribution of CSs to the intermittency in turbulent channel flow of surfactant solution decreases, indicating the inhibition of intermittency by surfactant additive. In order to investigate the drag-reducing characteristics at different locations along the wall-normal direction, the fluctuation velocity fields in the streamwise-spanwise planes at different wall-normal locations are decomposed by two-dimensional WT. The results show that surfactant additive mainly affects the flow in the near-wall region (especially in the buffer layer) and thus induces drag reduction effect.

Regular Unknown Input Functional Observers for 2-D Singular Systems

Lu Wang,Huiling Xu,Yun Zou 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.5

This paper concerns with asymptotic regular unknown input functional observers (UIFOs) for two-dimensional (2-D) acceptable singular systems described by the Fornasini-Marchesini local state-space second model. A sufficient condition for the existence of an asymptotic regular UIFO is first presented in terms of a rank condition on the given system matrices. Based on this, an asymptotic 2-D regular UIFO is constructed using a linear matrix inequality (LMI) technique, while a new method is also given for designing regular functional observers for 2-D acceptable singular systems. Two illustrative examples are provided to demonstrate the feasibility and effectiveness of the proposed method.

Violet Laser Acupuncture—Part 2: Effects on Peripheral Microcirculation

Lu Wang,Tao Huang,Weibo Zhang,Gerhard Litscher 사단법인약침학회 2011 Journal of Acupuncture & Meridian Studies Vol.4 No.1

Laser Doppler flowmetry for microcirculation monitoring was performed in 10healthy volunteers (mean age ± SD: 24.9 ± 3.3 years; 5 females, 5 males) prior to,during, and after stimulation using a noninvasive violet (405 nm) laser needle at the Dazhui (GV14) acupoint. The results of this controlled study (control point at the shoulder) showed significant (p < 0.05) increases in Flux (product of concentration and velocity of erythrocytes) at a distance of 3 cm from the acupoint. At the same time, no changes were found at the control point. Furthermore, 5 minutes after stimulation the microcirculation still flowed at a higher level than baseline values at the beginning of the investigation. In a single individual it was demonstrated that needle acupuncture enhanced this effect and placebo (deactivated laser) did not have a significant effect. The results suggest that violet laser acupuncture at the acupoint Dazhui can increase vascular effects on microcirculation.

Full-scale tests and analytical model of the Teflon-based lead rubber isolation bearings

Lu Wang,Jin Ou,Weiqing Liu,Shuguang Wang 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.48 No.6

Base isolation is widely used in seismic resisting buildings due to its low construction cost, high reliability, mature theory and convenient usage. However, it is difficult to design the isolation layer in highrise buildings using the available bearings because high-rise buildings are characterized with long period, low horizontal stiffness, and complex re-distribution of the internal forces under earthquake loads etc. In this paper, a simple and innovative isolation bearing, named Teflon-based lead rubber isolation bearing, is developed to address the mentioned problems. The Teflon-based lead rubber isolation bearing consists of friction material and lead rubber isolation bearing. Hence, it integrates advantages of friction bearings and lead rubber isolation bearings so that improves the stability of base isolation system. An experimental study was conducted to validate the effectiveness of this new bearing. The effects of vertical loading, displacement amplitude and loading frequency on the force-displacement relationship and energy dissipation capacity of the Teflon-based lead rubber isolation bearing were studied. An analytical model was also proposed to predict the force-displacement relationship of the new bearing. Comparison of analytical and experimental results showed that the analytical model can accurately predict the force-displacement relationship and elastic shear deflection of the Teflon-based lead rubber isolation bearings.

Study on Microstructure and Mechanical Properties of CrCuFeNiV Multi Principal Element Alloy

Lu Wang,Zhengzhong Feng,Hongwei Niu,Qi Gao,Mingqin Xu,Lin Yang,Jiaojiao Yi 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.12

Phase constitution, microstructure, and mechanical properties of the as-cast and homogenized CrCuFeNiV multi principalelement alloys were investigated. Results show that the microstructures of CrCuFeNiV alloys either in the as-cast orhomogenized state were constituted by the dispersed Cu-rich fcc regions and the matrix regions (intertwined bcc + σ phases). Thereinto, the σ phase, ranged from nanometers to microns, was a complex multicomponent intermediate phase with a highsolubility for Fe, Cr, Ni, and V. This phase structure and hardness had an impressive thermal stability, which was evidencedby the current annealing treatment. High hardness (822 HV and 793 HV) was simultaneously achieved under an appliedload of 200 g in the as-cast and homogenized CrCuFeNiV alloys, on account of the incorporation of the high-stiffness σphase against the fcc and bcc phases. The ultimate compressive strength of ~ 1490 MPa was obtained in the as-cast alloydue to the high deformation resistance to the dislocation movement of bcc phase and precipitation strengthening of σ phaseat the expense of plasticity. The deterioration in plasticity was attributed to the stress concentration easily triggered by thehard and brittle σ phase.

The New Bubble–Slurry for Sand Conditioning during EPB Shield Tunnelling: A Laboratory Scale Study

Lu Wang,Wei Zhu,Yongjin Qian,Huitang Xing 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.5

Spewing is a key issue during earth pressure balance (EPB) shield tunneling in a water-rich sandy stratum. This paper proposed the bubble–slurry as a new type of soil conditioning agent. The foamability and stability of the bubble–slurry were studied, and the volume stability, fluidity, and permeability of bubble–slurry-conditioned sands with hydraulic gradient of 2 to 10 were analyzed. The stability mechanism was explored by the zeta potential and microstructure of the bubble–slurry system. The formulation of bubble–slurry with a half-life of 121 – 383 h was determined through laboratory tests. The results of soil conditioning experiments showed that the bubble–slurry-conditioned soil exhibited appropriate fluidity, excellent volume stability and low permeability in a certain period. The use of bubble–slurry can save approximately 3.0–8.2% of the slurry consumption compared with the method of slurry conditioning. The zeta potential and the distribution of slurry particles of the bubble–slurry system were key mechanisms affecting the stability of the bubble–slurry. The high absolute value of zeta potential of the system increases the dispersion of bubbles, and the slurry particles uniformly distributed on the bubble liquid film and in the Plateau boundary are conducive to enhancing the anti-disturbance ability and inhibiting the decay of bubbles.

On Objective Functions for Fixed-Outline Floorplanning

Lu Wang,Xiaolin Zhang,Song Chen,Takeshi Yoshimura 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7

Fixed-outline floorplanning enables multilevel hierarchical design, where aspect ratios and area of floorplans are usually imposed by higher level floorplanning and must be satisfied. Simulated Annealing is widely used in the floorplanning problem. It is well-known that the solution space, solution perturbation, and objective function are very important for Simulated Annealing. In this paper, we focus on the objective functions used in FOFP problem. Up to now, many kinds of objective functions were proposed in the existing researches, but those objective functions had many limitations, and the applicable situation is not clearly. We summarize and analyze the existing objective functions used in Fixed-Outline floorplanning methods, and then suggest some new objective functions respectively used in the fixed-oultine floorplanning with and without wire-length optimization, respectively.

Microarchitectural Silk Fibroin/Hyaluronic Acid Scaffold via Slight Biodegradation

Lu Wang 한국섬유공학회 2021 Fibers and polymers Vol.22 No.7

Silk-based scaffolds with hierarchical structure possess the capacities of promoting cells adhesion, proliferation and neotissue formation, which have been one of the candidates in tissue engineering. However, the ways to construct hierarchical structures in scaffolds are very limited, rather than introducing other nanoscale components. In this study, a hierarchical porous structure was directly established in silk fibroin/hyaluronic acid (SF/HA) scaffold through slight degradation technique. The resulting SF/HA scaffold presented desirable microarchitecture and appropriate porosity attribute to partial hydrolysis of SF molecules. The compression test showed that the SF/HA scaffolds was better than SF scaffolds in terms of compression stress and Young’s modulus. More importantly, the SF/HA scaffolds displayed good cytocompatibility as to supporting cells adhesion and proliferation. This paper provides a new strategy for preparing SF-based scaffolds with hierarchical porous structure in tissue engineering.

Anti-Obesity and Hypolipidemic Effects of Boussingaultia gracilis Miers var. pseudobaselloides Bailey in Obese Rats

Lu Wang,Chae-Young Bang,정세영 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.1

Boussingaultia gracilis Miers var. pseudobaselloides Bailey is used as a Chinese folk medicine for treatment of diabetes, inflammation, and liver disease. The present study is to investigate the anti-obesity and hypolipidemic effects of B. gracilis Miers var. pseudobaselloides Bailey ethanol extract (BGE). Six-week-old Sprague–Dawley male rats were separately fed for 6 weeks with two kinds of diets—a normal diet (ND) and a high-calorie high-fat diet (HD). Then the animals were treated with tea catechin (100mg/kg) or BGE (300, 600, or 900mg/kg) for another 6 weeks. BGE significantly lowered body weight gain, fat-pad weights, and serum and hepatic lipid levels in HD-induced obese rats. The lipid droplets in hepatic tissue of BGE-treated groups were also markedly lessened compared with HD group rats via oil red O staining. Significant increases were observed in the expressions of genes for peroxisome proliferator-activated receptor (PPAR) α and for fatty acid oxidation and thermogenesis-related proteins—acyl-coenzyme A oxidase, carnitine palmitoyl transferase-1, and uncoupling protein-2—in the liver of the BGE-treated groups. Moreover, BGE was found to suppress the expression of sterol response element binding protein-1, a lipogenic gene, as well as those of fatty acid synthase and PPARγ in adipose tissue and liver of HD group rats. These results indicate that B. gracilis Miers var. pseudobaselloides Bailey may have an anti-obesity and hypolipidemic effect through regulation of expression of genes involved in lipolysis and lipogenesis.