Preparation of new visible-light driven nanocomposite photocatalysts, X/NaTaO3/Er3+:YAlO3 (X = Ag, Au and Pt), for photocatalytic conversion of Cr(VI)

Bowen Li,Yidi Wang,Fangyuan Tian,Guanshu Li,Zhaohong Zhang,Jun Wang,Youtao Song 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.54 No.-

In order to expand the light response range of wide band-gap semiconductor photocatalyst (NaTaO3) for effective photocatalytic conversion of Cr(VI), an up-conversion luminescence agent (Er3+:YAlO3) is combined with NaTaO3 and a visible-light driven photocatalyst, NaTaO3/Er3+:YAlO3, is prepared. Moreover, several conduction band co-catalysts (Ag, Au and Pt) are deposited the surface of NaTaO3/Er3+: YAlO3, respectively, to facilitate the transfer rate of photo-generated electrons. X-ray diffractometer (XRD), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) analyses are employed to confirm the morphology, microstructure and composition of the prepared photocatalysts. In addition, UV–vis diffuse reflectance spectra are determined to explore the visible-light absorption properties of Er3+:YAlO3, NaTaO3, NaTaO3/Er3+:YAlO3 and X/NaTaO3/Er3+:YAlO3 (X = Ag, Au and Pt). Photoluminescence (PL) spectra are used to estimate the recombination rate of electron–hole pairs. The effects of irradiation time, photosource kind, solution acidity and used times on the photocatalytic capabilities of NaTaO3/Er3+:YAlO3 and X/NaTaO3/Er3+:YAlO3 (X = Ag, Au and Pt) are investigated in detail. The results show that the uses of up-conversion luminescence agent (Er3+:YAlO3) and co-catalysts (Ag, Au and Pt) can promote NaTaO3 to utilize visible-light to carry out the photocatalytic conversion of Cr(VI). Particularly, the prepared Au/NaTaO3/Er3+:YAlO3 nanocomposite with 1.0 wt% Au and 0.3:1.0 molar ratio of Er3+:YAlO3 and NaTaO3 shows the highest photocatalytic activity in conversion of Cr(VI).

Circuit Model for the Effect of Nonradiative Recombination in a High-Speed Distributed-Feedback Laser

Bowen Nie,Zhijuan Chi,Qing-an Ding,Xiang Li,Changqing Liu,Xiaojuan Wang,Lijun Zhang,Juan Song,Chaofan Li 한국광학회 2020 Current Optics and Photonics Vol.4 No.5

Based on single-mode rate equations, we present an improved equivalent-circuit model for distributedfeedback (DFB) lasers that accounts for the effects of parasitic parameters and nonradiative recombination. This equivalent-circuit model is composed of a parasitic circuit, an electrical circuit, an optical circuit, and a phase circuit, modeling the circuit equations transformed from the rate equations. The validity of the proposed circuit model is verified by comparing simulation results to measured results in the literature. The results show that the slope efficiency and threshold current of the model are 0.22 W/A and 13 mA respectively. It is also shown that increasing bias current results in the increase of the relaxation-oscillation frequency. Moreover, we show that the larger the bias current, the lower the frequency chirp, increasing the possibility of extending the transmission distance of an optical-fiber communication system. The results indicate that the proposed circuit model can accurately predict a DFB laser’s static and dynamic characteristics.

In-Situ Observation of Grain Refinement in the Simulated Heat-Affected Zone of High-Strength Low-Alloy Steel by Zr-Ti Combined Deoxidation

Bowen Zhou,Guangqiang Li,Xiangliang Wan,Yu Li,Kaiming Wu 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.2

The effect of Zr-Ti combined deoxidation on the grain refinement in the simulated coarse-grained heat-affected zone of a high-strength low-alloy steel was investigated by means of analytical characterization techniques such as in-situ microscopy, transmission electron microscopy, and electron backscattered diffraction analysis. Owing to the Zr-Ti combined deoxidation, a large amount of fine Zr-Ti oxide particles were formed in the steel and retarded the austenite grain growth during simulated welding thermal cycle. The austenite grains were small and uniform. The Mn can diffuse spontaneously from austenite to Zr-Ti oxide inclusion and MnS precipitated on ZrO2, which can form Mn depleted zone in the vicinity of inclusion. The acicular ferrite grains nucleated on intragranular Zr-Ti oxide inclusions in austenite grains grew in different directions and effectively divided the austenite grain into several finer and separate regions at intermediate temperature. The crystallographic grain size became small in the simulated coarse-grained heat-affected zone of Zr-Ti-killed steel due to the effective pinning effect by Zr-Ti oxide particles and acicular ferrite formation.

Development of a Directly Self-adaptive Robot Hand with Pulley-belt Mechanism

Guoxuan Li,Bowen Li,Jie Sun,Wenzeng Zhang,Zhenguo Sun,Qiang Chen 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

Directly self-adaptive under-actuated (DSUA) hands have great potential to stably grasp different objects in unstructured environments. This paper develops a DSUA Hand based on multi-pulley-belt mechanism, which consists of 5 fingers and has 14 DOF. Self-adaptation is designed as the main function of it. The stability of DSUA hand’s grasping process does not highly depend on control algorithm, sensors or control system. This DSUA fingers are based on multi-pulley-belt mechanism. A mathematical model of the 3-joint finger’s contact force is given. Contact force analyses of the DSUA finger are discussed in detail. DSUA Hand weighs 0.94 kg and can grasp objects up to 0.6 kg. The grasping adaptation of DSUA hand is certified by grasping experiments of different objects.

Calculation of cavitation evolution and associated turbulent kinetic energy transport around a NACA66 hydrofoil

Xiaojun Li,Bowen Li,Benxu Yu,Yun Ren,Bo Chen 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.3

The physical mechanism of flow unsteadiness is one of the key problems in cavitating flow. Significant efforts have been exerted to explain the cavitation-vortex interaction mechanism. As well, the process of kinetic energy transport during the evolution of unsteady cavitating flow must be elucidated. In this work, 2D calculations of cavitating flow around a NACA66 hydrofoil were performed based on the open source software OpenFOAM. The modified shear stress transport k-ω turbulence model, which considers curvature and turbulent eddy viscosity corrections, was employed to close the governing equations. The Schnerr-Sauer cavitation model was adopted to capture the cavitation phase change process. Numerical results showed reasonable consistency with the results of the experiments conducted by Leroux et al. (2004). The results showed that cavitation promotes turbulence intensity and flow unsteadiness around the hydrofoil. During the attached sheet cavity growth stage, high-value regions of turbulent kinetic energy are located substantially at the interface of the cavity, particularly at the rear portion of the cavity region. During the cloud cavity shed-off stage, the cavity begins to break off and the maximum value of turbulent kinetic energy is observed inside the shed cavity. Finally, the influence of cavitation on the turbulence intensity is illustrated using the turbulent kinetic energy transport equation, which shows that the pressure diffusion and turbulent transport terms dominate as cavitation occurs. In addition, cavitation promotes turbulence production and increases dissipation with fluid viscosity and flow unsteadiness. The viscous transport term only acts in the cavitation shedding stage under large-scale vortex shedding. Overall, these findings are of considerable interest in engineering applications.

Bandgap Engineering of Monolayer MoS2 under Strain: A DFT Study

Can Li,Bowen Fan,Weiyi Li,Luowei Wen,Yan Liu,Tao Wang,Kuang Sheng,You Yin 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.11

In this paper, density functional theory calculations are used to investigate the monolayer MoS2 in terms of the strain by analyzing the structure parameters: the bandgap, the density of states (DOS) and the Milliken charges. The calculations indicate that an increasing external stain tends to depress the ripple structure with a shorter S-S interlayer spacing and to enlarge the length of the Mo-S bond. Tensile strain dramatically alteres the bandgap; however, compressive strain almost does not. The change in the bandgap is explained by an analysis of the DOS, the partial density of states (PDOS), the structure parameters and the Mulliken charge distribution. The effects of strain on the Mulliken charge and the length of the Mo-S band cause bandgap differences under tensile and compressive strain.

Direct catalytic conversion of glucose and cellulose

Li, Zhenhuan,Su, Kunmei,Ren, Jun,Yang, Dongjiang,Cheng, Bowen,Kim, Chan Kyung,Yao, Xiangdong The Royal Society of Chemistry 2018 GREEN CHEMISTRY Vol.20 No.4

<P>Biomass product 5-hydroxymethylfurfural (5-HMF) can be used to synthesize a broad range of value added compounds currently derived from petroleum. Thus, the effective conversion of glucose or cellulose (the major components of biomass) into fuels and chemical commodities has been capturing increasing attention. Previous studies have been extensively focused on a two-step process for producing 5-HMF from glucose or cellulose, <I>i.e.</I>, the isomerization of glucose into fructose and then the dehydration of fructose. We herein discovered that heterogeneous sulfonated poly(phenylene sulfide) (SPPS) containing strong Brønsted acid sites is able to convert glucose and cellulose into 5-HMF with a high yield in ionic liquids (ILs). The optimal activity of glucose conversion to 5-HMF achieves a yield of 87.2% after 4 h reaction at 140 °C. For direct cellulose conversion, a 5-HMF yield of 68.2% can be achieved. The reaction mechanism over the SPPS catalyst in ILs was studied by DFT calculations, and the results indicated that the SO3H group of SPPS plays a crucial role in glucose conversion into 5-HMF, and it acts as a proton donor as a Brønsted acid and functions as a proton acceptor as the conjugate base. Furthermore, the anions and cations of ILs together with SO3H-SPPS helped in stabilizing the reaction intermediates and transition states, which also resulted in glucose facile conversion into 5-HMF. The new catalyst system highlights new opportunities offered by optimizing the production of 5-HMF directly from glucose and cellulose.</P>

Modeling and Virtual Screening of Antisense Peptides Targeting the Divergent Region of Tumor-Associated MT1-MMP Protein

Bowen Tan,Yijie Zhou,Zhilei Song,Yinxuan Peng,Fang Wu,Yue Kang,Xiaomin Liu,Li Zeng,Tingting Huang,Zongying Liu,Lili Xiong,Zhiyun Guo,Jian Cui,Canquan Mao 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.9

Membrane type-1 matrix metalloproteinase (MT1-MMP; also known as MMP14) is a key enzyme involved in tumor invasion and metastasis, and is a potential target for drug discovery for cancer therapy. However, till now there is no MT1-MMP- or MMP-based anticancer drugs in the market mainly because of the high conservation of the MMP family and also because there is no elucidated crystal structure for the mature MT1-MMP. The modeling of the three-dimensional structure of mature MT1-MMP and the finding of MT1-MMP targeted peptides by virtual screening are highly desired. In this study, the three-dimensional structure of mature MT1-MMP is constructed by homology and de novo modeling and later rationalized and optimized by molecular dynamics simulations. An antisense peptide library was constructed against the divergent sense peptide DEGTEEET in the specific region of MT1-MMP, which was found by multiple alignment of the whole MMP family. The antisense peptide library was virtually screened against the constructed three-dimensional model of MT1-MMP. The top 20 novel peptides were further studied, which were found well docked with MT1-MMP at the region of DEGTEEET, again confirming their specific binding to MT1-MMP. Preliminary study of one of the top-ranked peptide SFLLSPFV showed that it could inhibit the viabilities of MG63 and MDA-MB-231 tumor cells. We thus not only successfully modeled the three-dimensional structure of mature MT1-MMP but also provided a new way for the finding of peptide candidates targeting MT1-MMP based on antisense peptide library.

Microcapsules derived from Pickering emulsions as thermal latent curing accelerator for epoxy resins

Bowen Zhang,Yingying Zhao,Xin Sun,Xiaoma Fei,Weiwei Wang,Xiaojie Li,Xiaoya Liu 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.83 No.-

Organic-inorganic hybrid microcapsules encapsulating 2-phenylimidazole (2-PhIm) were prepared byPickering emulsion polymerization of styrene and divinyl benzene using methacryloyloxy silanemodifiedsilica particles as the stabilizer, and served as a thermal latent curing accelerator fordiglycidylether of bisphenol A epoxy/anhydride system. The one-component curing compositioncontaining 5 wt% of the microcapsules exhibited an excellent storage stability. The pot life at roomtemperature was as long as 30 days, while which of 2-PhIm curing system was only 2 days. At elevatedtemperature, the encapsulated 2-PhIm could be released from microcapsules effectively, and instantlyaccelerated the curing reaction. Meanwhile, the addition of microcapsules did not cause an adverse effecton the thermomechanical performance of the epoxy thermosets. In addition, the latency and curingbehavior could be facilely regulated at a wide range of temperature by adjusting monomer ratios of thepolymer matrix, to match different process temperatures. The microcapsules with robust cross-linkedpolystyrene matrix structure also showed good resistance to shearing forces, indicating their feasibilityfor high-speed mixing or kneading process in practical applications. It is suggested that the novel latentcuring accelerator is potential for high-performance one-pot epoxy formulations, particularlyrecommended for application in electronic packagingfields.

Design and Output Characteristic Analysis of 3-D Micron-scale Actuator

Yafang Li,Bowen Wang,Wenmei Huang 한국자기학회 2020 Journal of Magnetics Vol.25 No.1

A new type of 3-D micron-scale actuator is designed, which is mainly composed of four Galfenol rods, drive coils, base, magnetic yoke and output head. According to magnetostrictive model and structural dynamic model, the output characteristics of the actuator have been analyzed. The 3-D moving trail of the output head is controlled by the drive coils of the four rods. The actuator prototype is fabricated and experimental investigated. Good agreement is observed between the simulation and experimental results. The maximum output displacements of the X, Y and Z direction are 46 μm, 46 μm and 8.2 μm. Furthermore, when a pair of opposing rods works, the actuator has two modes of vibration under 1000 Hz. The resonant frequencies of the actuator are 522 Hz in Y direction and X direction. The results have proved that the actuator can realize varied 3-D displacement according to actual demands, and can be used in 3-D micron-scale field, such as surface mold polishing.