Facile and highly effective synthesis of nitrogen-doped graphene quantum dots as a fluorescent sensing probe for Cu2+ detection

Bo Gao,Da Chen,Bingli Gu,Ting Wang,Zihao Wang,Feng xie,Yongsheng Yang,Qinglei Guo,Gang Wang 한국물리학회 2020 Current Applied Physics Vol.20 No.4

Nitrogen-doped graphene quantum dots (N-GQDs) with high blue fluorescence efficiency were synthesized by the hydrothermal method from p-Phenylenediamine and p-Coumaric acid. The N-GQDs possess several superiorities, most significantly in excellent solubility and superior photostability. Besides, the as-prepared N-GQDs exhibit a uniform size distribution with a diameter of about 3.8 ± 0.5 nm. After dispersing the N-GQDs in water, the formed aqueous solution still presents a stable and homogeneous phase even after 2 months at room temperature. The N-GQD dispersion was further utilized as sensing probes for the selective detection of copper ions (Cu2+), which is realized by the photoluminescence (PL) quenching of N-GQDs after adding Cu2+. The detection limit for Cu2+ was found to be 57 nM L−1, with superior selectivity in the presence of other commonly interfering metal ions. The presented results in this study provide a facile and high-efficiency method for synthesizing N-GQDs, with ultra-high detectivity and selectivity for Cu2+ detection, offering numerous opportunities for the development of biosensing, bioimaging, environment monitoring, and others.

Novel RGO and Concave Cube Cu2O Co-modified BiVO4 Nanosheets with Enhanced Photocatalytic and Surface Adsorption Performances of Tetracycline

Xin Gao,마창창,Wei Ma,Rongru Chen,Yang Liu,Zhi Liu,Zhi Zhu,Pengwei Huo,Yongsheng Yan 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.2

A novel ternary Cu2O/BiVO4/RGO photocatalyst is successfully constructed by hydrothermal and evaporation-induced method, and it exhibits superior photocatalytic performance for degradation tetracycline (TC). Meanwhile, the visible light absorption range of composite photocatalyst is effectively broadened by the formation of heterojunction with narrow band gap semiconductor Cu2O. And the separation efficiency of the photogenerated electron–hole pairs is significantly enhanced by the synergistic effect of Cu2O and RGO. More importantly, the adsorption of TC by ternary Cu2O/BiVO4/RGO possesses high adsorption capacity, which is 23.73 times higher than that of pure BiVO4. Additionally, the possible reaction mechanism is clearly revealed by radical trapping experiment, electron spin-resonance (ESR) spectroscopy. This work provides a new insight to design a photocatalyst with excellent adsorption to remove organic contaminants in water.

Effect of Composite Modification of Nickel Slag Powder and Polypropylene Fiber on Mechanical Properties of MKPC Mortar

Zhongzhe Zhang,Yongsheng Ji,Zhanguo Ma,Zhishan Xu,Furong Gao,Qi Xue 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.4

In order to explore the influence of nickel slag powder (Ni) and polypropylene fiber (PP) on the performance of MPKC mortar, different mass fractions of Ni (5% − 20%) and different volume fractions (0.6% and 1.0%) of PP were added to MKPC. The composite modified MKPC (CM-MKPC) specimens were tested and analyzed for flexural strength, compressive strength, split tensile strength, and bending performance. With the help of scanning electron microscope, the microstructure and fracture morphology of the modified MKPC specimens for related research. The results show that the addition of PP and Ni improves the mechanical properties of MKPC and improves its flexibility and deformation properties. When the content of Ni and volume of PP are 15% and 1.0%, respectively, the mechanical properties and bending properties of the modified MKPC mortar are the largest in the same group. Ni added to the MKPC gel system can reduce the friction between irregular magnesium oxide particles and between aggregates. In this way, PP fiber can well enter into the aggregate and play a bridging role at the interface, so that MKPC can better play its mechanical properties.

Producing magnetite concentrate via self-magnetization roasting in N2 atmosphere: Phase and structure transformation, and extraction kinetics

Qi Zhang,Yongsheng Sun,Yuexin Han,Yanjun Li,Peng Gao 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.104 No.-

In this work, a green self-magnetization roasting technology for producing magnetite was proposed withoutadding additional. The regulatory mechanisms of the main factors (siderite dosage, roasting temperature,and roasting time) on the self-magnetization roasting process were investigated. In-situ kinetic ofthe self-magnetization roasting process was analyzed by the infrared gas analyzer, and the phase transformationwas investigated by in-situ X-ray diffraction and Mössbauer. Under the optimal roasting conditionsof 30% siderite dosage, 730 C, and 7.5 min, the iron concentrate with Fe grade 68.82% and Ferecovery 99.48% was obtained. The kinetic and phase transformation results indicated that the selfmagnetizationroasting process was divided into two stages: siderite pyrolysis in the prophase stage,and hematite reduced to magnetite by reductant (FeO and CO) from siderite pyrolysis in the anaphasestage. The SEM analyses showed that the newborn magnetite crystals were mainly coarse-grained andneedles, which fitted the kinetics characteristics for the Nucleation model. Using self-magnetizationroasting technology, siderite and hematite would promote mutual reduction to improve product magnetismand roasting efficiency without adding reductant. Also, self-magnetization roasting will enhancethe utilization rate of siderite, and it contributes to energy conservation and CO2 emission reduction.

Growth behavior and kinetics of magnetite during magnetization roasting

Qiang Zhang,Yongsheng Sun,Shuai Wang,Yuexin Han,Yanjun Li,Peng Gao 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.116 No.-

The magnetization roasting of hematite with two particle sizes was performed to investigate the growthbehavior and kinetics of magnetite. The magnetite exhibited comparable growth trends throughout themagnetization roasting process at different roasting temperatures, and enhancing the roasting temperaturecan facilitate the growth of magnetite. The nascent magnetite nuclei appeared acicular, predominantlydeveloped along the edges and fissures of the hematite particles before progressively growinginward. Moreover, the temperature stress and magnetite formation led to the loose and porous structureof the nascent magnetite particles. The growth kinetics demonstrated that the growth process of magnetitecould be divided into induction period and growth period based on the different growth rates. For the same hematite sample, the growth rate of magnetite in the induction period was lower than thatin the growth period. The magnetization roasting of hematite with a smaller particle size may be completedin a shorter time, even if increasing the particle size of hematite can accelerate the growth rateof magnetite. The growth kinetic models were established based on the parabolic law, and the reliabilityof describing the growth process of magnetite was verified by comparing the predicted values with theexperimental values.

Effect of Polyacrylamide on Rheological Properties of Underwater Non-dispersible Paste of Alkali-Activated Slag

Zhongzhe Zhang,Yongsheng Ji,Zhanguo Ma,Furong Gao,Mingming Ma,Zhishan Xu 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.1

In this paper, the rheological parameters of the alkali-activated slag underwater non-dispersible paste (AAS-UNDP) were tested, and the influence of polyacrylamide (PAM) on the rheological property of AAS-UNDP was studied combing with the method of molecular dynamics simulation. The experimental results show that the rheological model of AAS-UNDP and cement basted underwater non-dispersible paste (CB-UNDP) are consistent with the Herschel-Bulkley model. The results of molecular dynamics simulation show that the anions in PAM and the OH- alkali-activated slag cementitious material (AASCM) can produce repulsive force, so the potential energy of the AASCM is lower than the potential energy of the cement based cementitious material (CBCM).The mean square displacement (MSD) value and self-diffusion coefficient of PAM in the AASCM are higher than those of CBCM, indicating that the diffusion rate of particles in the AASCM is better than that of CBCM.

Design and evaluation of a 7-DOF cable-driven upper limb exoskeleton

Feiyun Xiao,Yongsheng Gao,Yong Wang,Yanhe Zhu,Jie Zhao 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.2

This paper presents a seven degrees of freedom cable-driven upper limb exoskeleton (CABXLexo-7), which is compact, lightweight, and comfortable for post-stroke patients. To achieve the compactness of exoskeleton, two types of cable-driven differential mechanisms were designed. The cable-conduit mechanisms were applied to transmit the power of motors mounted on the backboard to the corresponding joints, then the whole weight of the exoskeleton could be light to ensure a comfortable motion assistance. In the course of experiments, the surface electromyography signals of major muscles related with the movements of upper limb were collected to evaluate the assistant ability of exoskeleton. The experimental results showed that the activation levels of corresponding muscles were reduced by using the seven degrees of freedom cable-driven upper limb exoskeleton in the course of rehabilitation, and it demonstrated that the exoskeleton can provide effective movements assistance to the post-stroke patients.

Pyrolysis mechanism of bastnaesite during roasting in N2 atmosphere: An in-situ study of gas products, phase transition, and kinetics

Qiang Zhang,Yongsheng Sun,Yuexin Han,Peng Gao,Wenbo Li 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.124 No.-

The application of suspension magnetization roasting technology in ferruginous rare earth bearing orehas gained significant attention. Bastnaesite, due to its pyrolysis characteristics, has been proposed asa reductant for iron minerals. In this study, the pyrolysis of bastnaesite was investigated through variousin-situ methods. The results showed that during pyrolysis, CeOF and CO2 were first generated, followedby the reaction of CO2 with Ce2O3 and Ce7O12 to produce CO. Pyrolysis occurred initially on the particlesurface and then progressed inward. Increasing the roasting temperature promoted the pyrolysis of bastnaesiteand CO generation. The addition of CO2 during the roasting process enhanced the formation of CO. The pyrolysis kinetic mechanisms under isothermal and non-isothermal conditions were phaseboundarycontrolled reaction mechanism (n = 4) and phase-boundary controlled reaction mechanism(n = 2–4), respectively. This detailed analysis of the pyrolysis behavior of bastnaesite facilitates the efficientand low-carbon development of ferruginous rare earth ores through suspension magnetizationroasting.

Ag Nanoparticles Decorated N-Doped Carbon Black as a High-Performance Catalyst for Catalytic Hydrogenation of p-nitrophenol

Jing Chen,Yanting Gao,Yongsheng Fu,Shugang Pan 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.8

Ag nanoparticles decorated N-doped carbon black with different Ag content was synthesized via a straightforward method. The catalysts have been conducted in the catalytic hydrogenation of nitrophenols in the presence of sodium borohydride. The results show that Ag4/NCB possesses the highest catalytic activity for the catalytic hydrogenation of p-nitrophenol (p-NP) to p-aminophenol (p-AP). The significant enhancement in catalytic activity can be attributed to the high dispersity and smaller size of Ag nanoparticles, and remarkable synergistic effect of the combination of Ag nanoparticles and N-doped carbon black.

Acid-Base Bifunctional Metal-Organic Frameworks: Green Synthesis and Application in One-Pot Glucose to 5-HMF Conversion

Yunlei Zhang,Pei Jin,Minjia Meng,Lin Gao,Meng Liu,Yongsheng Yan 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.11

The direct synthesis of metal-organic frameworks (MOFs) with acidic and basic active sites is challenging due to the introduction of functional groups by post-functionalization method often jeopardize the framework integrity. Herein, we report the direct synthesis of acid-base bi-functional MOFs with tuning acid-base strength. Employing modulated hydrothermal (MHT) approach, microporous MOFs named UiO-66-NH2 was prepared. Through the ring-opening reaction of 1,3-propanesultone with amino group, UiO-66-NH2-SO3H-type catalysts can be obtained. The synthesized catalysts were well characterized and their catalytic performances were evaluated in one-pot glucose to 5-HMF conversion. Results revealed the acid-base bi-functional catalyst possessed high activity and excellent stability. This work provides a general and economically viable approach for the large-scale synthesis of acid-base bi-functional MOFs for their potential use in catalysis field.