Room-temperature Synthesis of Cu2O Nanostructures and Their Morphology-dependent Adsorption Properties

Yanyan Xu,Ping Liu,Yanyan Cao,Yaqiu Sun,Guoying Zhang 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.7

Three different Cu2O nanostructures, namely porous nanospheres, nanoparticles, and nanocubes, were synthesized through a facile solution route at room temperature. Structure and morphology of the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), and nitrogen adsorption–desorption isotherms. The adsorption behavior of Methyl Orange (MO) onto these Cu2O nanostructures was investigated, considering the effect of initial methyl orange concentration and the additive amount of Cu2O products. The kinetic and equilibrium investigations suggested that the adsorption process of MO followed a pseudo-second order rate equation and the Langmuir isotherm model. The maximum adsorption capacity of the three samples followed the sequence: porous nanospheres > nanoparticles > nanocubes, which was in accordance of the BET specific surface of the samples. In addition, further investigations indicated that the as-prepared Cu2O nanostructures also show good adsorption properties for other anionic dyes including Congo red and Methyl blue.

Hierarchical chitosan/polyvinyl alcohol/polyethylene glycol/nonwoven fabric micro/nanofiber composite membrane: a potential biomaterial for wound dressing

Ziwei Sun,Qingtao Liu,Zhen Wang,Baobao Zhao,Quan Feng,Yanyan Sun,Min Zhong 한국고분자학회 2023 Macromolecular Research Vol.31 No.12

A hierarchical chitosan/polyvinyl alcohol/polyethylene glycol/nonwoven fabric (CS/PVA/PEG/NWF) micro/nanofiber composite membrane (CM) was prepared via electrospinning as a potential wound dressing. The polyester/viscose NWF acting as a substrate to receive the nanofiber layer was modified by alkali deweighting. Meanwhile, PEG with various additive amount was used to afford morphological regulation and control. As a result, the NWF modified with 7.5% NaOH solution exhibited a good hydrophilia and a superior dimensional stability based on smaller elongation at break and higher peel strength. In addition, the morphology of the nanofiber layer was closely related to PEG content. CS/PVA/PEG nanofiber with smaller diameter was spun when PEG content reached to 3.0%. Accordingly, the micro/nanofiber CM showed an opportune water absorption and good air permeability. Furthermore, neither hemolysis nor cytotoxicity phenomena appeared for the resultant CM, since the hemolysis rate and the cell viability were less than 5% and more than 70%, respectively.

Improvement of Wuyiencin Biosynthesis in Streptomyces wuyiensis CK-15 by Identification of a Key Regulator, WysR

( Yanyan Liu ),( Hojin Ryu ),( Beibei Ge ),( Guohui Pan ),( Lei Sun ),( Kyungseok Park ),( Kecheng Zhang ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.12

Wuyiencin is produced by Streptomyces ahygroscopicus var. wuyiensis CK-15 and is widely used as an antifungal agent in agriculture. Analysis of wuyiencin biosynthetic gene clusters reveals wysR, a member of the LAL-family of transcriptional regulatory genes. WysR consists of an Nterminal PAS domain and a LuxR family C-terminal helix-turn-helix motif. However, the roles of wysR in wuyiencin biosynthesis are largely unknown. In this study, we showed that inactivation of wysR resulted in the complete loss of wuyiencin production, which could be restored by complementation with a single copy of wysR. Furthermore, we successfully increased wuyiencin production to a significantly higher level by overexpression of wysR in S. wuyiensis CK-15. Quantitative real-time RT-PCR analysis showed that WysR regulates wuyiencin biosynthesis by modulating other putative regulatory genes. Thus, WysR was identified as an activator of wuyiencin biosynthesis, and overexpression of wysR gene proved to be an effective strategy for improving wuyiencin production.

A Novel Vibration Model for Explanation of the Frequency Features in Multistage Wind Turbine Gearboxes Considering the Effects of Inter-stage Meshing Frequency Modulation

Yanyan Nie,Fangyi Li,Liming Wang,Jianfeng Li,Yanle Li,Mingshuai Sun,Mengyao Wang,Guoyan Li 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.1

As a kind of green energy, wind energy has become cost-competitive mainstream energy in the world. The gearbox is one of the most important and vulnerable components in the wind turbine (WT), which suffers a high failure rate and downtime. It is of great significance to the condition monitoring and fault diagnosis of the WT gearbox. However, in the multistage WT gearbox, the vibrations generated from different stages are coupled, which leads to a complex vibration spectral structure and brings difficulties in condition monitoring and fault diagnosis. Aiming to understand the vibration frequency features of multistage WT gearboxes, a novel phenomenological vibration model is established and the spectral structure is deduced by using the Fourier series analysis. In the vibration model, the phenomenon of inter-stage meshing frequency modulation (ISMFM) is considered, which is clearly proposed for the first time. The theoretical derivations are validated by both simulation and engineering tests using a 2.0 MW industrial WT gearbox. The results show that under healthy conditions, in addition to the meshing frequencies and their harmonics of each stage, there are also ISMFM sidebands in the vibration spectrum of the multistage WT gearbox, and the amplitude of the sidebands will change with the health status of the gearbox. The findings are not only applicable to the WT gearbox studied in this paper, but also to other similar multistage gearbox systems, which can provide a priori spectral structure for a multistage gear transmission system to assist its condition monitoring and fault diagnosis.

Carbon Nanotube Paper as Anode for Flexible Lithium-Ion Battery

Xiaogang Sun,Zhenhong Liu,Neng Li,Xiaoyong Wu,Yanyan Nie,Zhipeng Pang,Lifu Yue,Hao Tang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.11

In this investigation, multiwalled carbon nanotube (MWCNT) paper consists of MWCNTs and cellulose was fabricated by traditional paper-making method. It was applied directly as negative electrode in flexible lithium ion battery to replace ordinary electrode which is combined with anode material and current collector. The electrochemical performances of the as-produced MWCNT paper (AMP) and carbonized MWCNT paper (CMP) were evaluated in this study. The morphology and structure of the MWCNT papers were observed by scanning electron microscopy (SEM). The electrochemical performance of the battery was operated by cell test and electrochemical impedance spectroscopy (EIS) measurement. The charging and discharging results indicated that the CMP behaves with higher capacity than AMP. And the EIS analysis showed that a lower charge transfer resistance can be obtained in the CMP. The excellent electrochemical performance verifies the feasibility of MWCNT papers as a promising candidate for the anode in flexible lithium ion battery.

Effects of Pyrolyzing and Phosphiding on Dibenzothiophene Hydrodesulfurization of MOF-Derived Ni2P

Liu Yanyan,Wang Zhiheng,Li Xin,Gao Ruiyao,Sun Jiong,Liu Jiankun,Yao Songdong 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.6

To investigate the potential utilization of MOF templates in hydrodesulfurization (HDS) of large sulfur-containing compounds, MOF-derived Ni 2 P was prepared and characterized by XRD, TG, SEM, TEM, XPS and Raman. The fi ndings indicate that MOF-derived Ni 2 P catalyst exhibits signifi cantly enhanced Hydrodesulfurization (HDS) activity compared to conventional unsupported Ni 2 P. A modifi ed pyrolysis and phosphiding condition allowed the stacking of central Ni atoms to be aggregated loosely, and morphology of MOF-derived Ni 2 P can be controllably transmitted from polyhedral to petal-like. A lower pyrolysis temperature tends to reduce density of Ni aggregates and cluster size of Ni 2 P(111), thereby facilitating the phosphiding of Ni aggregates and enhancing the catalytic activity of MOF-derived Ni 2 P in HDS process. Increasing the duration time of pyrolysis at lower temperatures does not accelerate the aggregation of particles, but makes petals on surface of MOF-derived Ni become thinner and eventually disappear, until coral-like nanosphere aggregates with uniform size are formed. The gradually elimination of MOF framework renders nickel aggregates more susceptible to phosphiding. The collapse of pore structure of MOF template can impact HDS activity of MOF-derived Ni 2 P. Prolonging pyrolysis time causes the spacing between Ni 2 P clusters to diminish, thereby signifi cantly decreasing reactivity of Ni 2 P-400-4-275 compared to Ni 2 P-400-2-275 in DBT–HDS.

Gearbox Fault Diagnosis Based on Two-Class NMF Network Under Variable Working Conditions

Wang Yinsong,Sun Tianshu,Liu Yanyan 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.6

The gearbox is an important part of the wind turbine, and it is also a part prone to failure. Most of the fault diagnosis methods for gearboxes lack the ability to adapt to changing operating conditions. Once the operating conditions change, it is necessary to relearn the object characteristics, otherwise it is prone to misjudgment. Therefore, this paper proposes a method based on a two-class non-negative matrix factorization (NMF) network to realize gearbox fault diagnosis under variable operating conditions without additional data. The method is divided into two parts: model training and fault diagnosis. The former takes the basic operating conditions as the benchmark. It extracts the local static characteristics of the fault samples, and trains them into classifi er models with diff erent diagnostic functions to construct a network. The latter uses the static distance obtained from the data input network of the new operating condition as an important indicator for detecting the occurrence of a fault and identifying the type of the fault. The experimental results based on the QPZZ-II rotating machinery vibration test stand show that compared with other methods, the algorithm proposed in this paper has a good application eff ect on the diagnosis under variable operating conditions

An Improved B-Spline Fitting Method with Arc-Length Parameterization, G2-Continuous Blending, and Quality Refinement

Kang Min,Yanyan Sun,Chen-Han Lee,Pengcheng Hu,Shanshan He 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.11

In computer numerical control machining, tool paths are typically represented with piecewise linear segments (GO1s), which lack G1 and G2 continuity and cause fluctuation of feed rate and acceleration. To improve the continuity of tool paths, some method, e.g., B-spline tool path fitting, is preferred. However, none of the currently B-spline fitting method satisfies all tool-path fitting requirements of arc-length parameterization, G2 continuity and smoothness across the whole path. The aim of this research is to derive an industrial-strength method for B-spline tool path fitting, satisfying all of the named requirements. The improvements cover the arc-length based parameterization, G2 continuity as well as numerically measure to improve the quality of B-spline tool paths. To achieve arc-length parameterization, a preliminary fitting is added to evaluate arc-length and guide the parameterization (i.e., knot vector assignment); for joint G2-continuity, a five-control-point B-spline which satisfies chord error and shape-preserving constraints is constructed to blend adjacent B-splines; and a method based on the Hausdorff distance between the fitted B-splines and the original polylines is used to evaluate the fitting quality, and an additional refinement procedure is employed when the evaluation finds any disqualification. Simulation and experiment results prove that the proposed methods are effective.

Electrochemical Performance of Lithium-Ion Capacitors Using Pre-Lithiated Multiwalled Carbon Nanotubes as Anode

Manyuan Cai,Xiaogang Sun,Yanyan Nie,Wei Chen,Zhiwen Qiu,Long Chen,Zhenhong Liu,Hao Tang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.4

Pre-lithiated multiwalled carbon nanotube anode was prepared by internal short circuit approach (ISC) for 5 min, 30 min, 60 min and 120 min respectively. Lithium ion capacitors (LICs) were assembled by using pre-lithiated multiwalled carbon nanotubes as anodes and activated carbon (AC) as cathodes. The structure of multiwalled carbon nanotubes and electrodes were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical performance of pre-lithiated multiwalled carbon nanotube electrodes and pristine carbon nanotube electrodes were tested by galvanostatic charge/discharge and electrochemical impedance. The results indicated that pre-lithiation carbon nanotubes greatly improved the charge/discharge performance of LICs. The energy density was four times than conventional electric double-layer capacitors (EDLCs) at the current density of 100 mA/g. The LICs achieved a specific capacitance of 59.3 F/g at the current density of 100 mA/g with 60 min pre-lithiatiation process. The maximum energy density and power density was 96Wh/kg and 4035W/kg, respectively. The energy density still remained about 89.0% after 1000 cycles. The LIC showed excellent supercapacitor performance.

Nonenzymatic Electrochemical Immunosensor Using Ferroferric Oxide–Manganese Dioxide–Reduced Graphene Oxide Nanocomposite as Label for α-Fetoprotein Detection

Wensi Jian,Chunping Wang,Zuanguang Chen,Yanyan Yu,Duanping Sun,Liping Han,Lijuan Shi 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.10

A novel nonenzymatic electrochemical immunosensor was fabricated for quantitative detection of α-fetoprotein (AFP). The immunosensor was constructed by modifying gold electrode with electrochemical reduction of graphene oxide-carboxyl multi-walled carbon nanotube composites (ERGO–CMWCNTs) and electrodeposition of gold nanoparticles (AuNPs) for effective immobilization of primary antibody (Ab1). Ferroferric oxide–manganese dioxide–reduced graphene oxide nanocomposites (Fe3O4@MnO2–rGO) were designed as labels for signal amplification. On one hand, the excellent electroconductivity and outstanding electron transfer capability of ERGO–CMWCNTs/AuNPs improved the sensitivity of the immunosensor. On the other hand, introduction of rGO could not only increase the specific surface area for immobilization of secondary antibody (Ab2) but also build a synergetic effect to reinforce the electrocatalytic properties of catalysts. Fe3O4@MnO2–rGO nanocomposites were characterized by scanning electron microscope, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Using AFP as a model analyte, the proposed sandwich-type electrochemical immunosensor exhibited a wide linear range of 0.01–50 ng · mL-1 with a low detection limit of 5.8 pg · mL-1. Moreover, the Fe3O4@MnO2–rGO-based peroxidase mimetic system displayed an excellent analytical performance with low cost, satisfactory reproducibility and high selectivity, which could be further extended for detecting other disease-related biomarkers.