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Yanmin Shen,He Wang,Zijun Liu,Weikun Li,Yuhua Liu,Jingjing Li,Hong-Liang Wei,Huayun Han 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.93 No.-
A new type of water-retaining, slow-release fertilizer (WSF) based on double-network hydrogels wasfabricated via the ion-crosslinking of sodium carboxymethyl cellulose and the free radical polymeriza-tion of polymerizable β-cyclodextrin (MAH-CD), polyethylene glycol dimethacrylate (PEGDA), acrylamide(AM), and acrylic acid (AA) with urea-loaded halloysite as an additive. The effects of the AM to AAmonomer ratio, the halloysite content, the AlCl3 content and the MAH-CD content on the swelling ratiowere studied. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), andthermogravimetric analysis (TGA) were applied to characterize the structure and properties of the WSF. The swelling behavior and water retention capacity of the fertilizer were investigated using a classicgravimetric method. The experimental results indicated that the presence of halloysite nanotubes clearlyadjusted the swelling and release properties of the WSF. Kinetic modeling indicated that the swellingmechanism and slow release behavior were consistent with a Fickian diffusion mechanism. Form theconsiderations of its properties and raw materials, the fertilizer developed here has a good prospect ofapplication and extension.
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Yumeng Wang,Yuhua Xu,Liang Shen,Chenglong Xu,Yunpeng Cheng 한국통신학회 2014 Journal of communications and networks Vol.16 No.2
In this research, we study the problem of opportunisticspectrum access (OSA) in a time-varying environment with fadingchannels, where the channel state is characterized by bothchannel quality and the occupancy of primary users (PUs). First,a finite-state Markov channel model is introduced to represent afading channel. Second, by probing channel quality and exploringthe activities of PUs jointly, a two-dimensional partially observableMarkov decision process framework is proposed for OSA. In addition,a greedy strategy is designed, where a secondary user selects achannel that has the best-expected data transmission rate to maximizethe instantaneous reward in the current slot. Compared withthe optimal strategy that considers future reward, the greedy strategybrings low complexity and relatively ideal performance. Meanwhile,the spectrum sensing error that causes the collision betweena PU and a secondary user (SU) is also discussed. Furthermore,we analyze the multiuser situation in which the proposed singleuserstrategy is adopted by every SU compared with the previousone. By observing the simulation results, the proposed strategy attainsa larger throughput than the previous works under variousparameter configurations.
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Wang, Yumeng,Xu, Yuhua,Shen, Liang,Xu, Chenglong,Cheng, Yunpeng The Korea Institute of Information and Commucation 2014 Journal of communications and networks Vol.16 No.2
In this research, we study the problem of opportunistic spectrum access (OSA) in a time-varying environment with fading channels, where the channel state is characterized by both channel quality and the occupancy of primary users (PUs). First, a finite-state Markov channel model is introduced to represent a fading channel. Second, by probing channel quality and exploring the activities of PUs jointly, a two-dimensional partially observable Markov decision process framework is proposed for OSA. In addition, a greedy strategy is designed, where a secondary user selects a channel that has the best-expected data transmission rate to maximize the instantaneous reward in the current slot. Compared with the optimal strategy that considers future reward, the greedy strategy brings low complexity and relatively ideal performance. Meanwhile, the spectrum sensing error that causes the collision between a PU and a secondary user (SU) is also discussed. Furthermore, we analyze the multiuser situation in which the proposed single-user strategy is adopted by every SU compared with the previous one. By observing the simulation results, the proposed strategy attains a larger throughput than the previous works under various parameter configurations.
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WENJING YUAN,LING ZHU,PING CHEN,ANJIAN XIE,HUI ZHANG,CUIPING WANG,YUHUA SHEN 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.4
The Fe3O4@C core/shell microspheres were fabricated via a two-step process. Fe3O4 microspheres were firstly prepared, and Fe3O4@C core/shell microspheres were subsequently fabricated using glucose as a carbon source by a hydrothermal route, in which the thickness of the carbon coating was about 20 nm. The resulting products were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectra (FTIR). The Nitrogen adsorption–desorption isotherms reveal their mesoporous structure and larger BET surface area (62.3 m2g-1). The Fe3O4@C core/shell microspheres possess ferromagnetism and high saturation magnetization (39.2 emu ⋅ g-1). Bovine hemoglobin (BHb) was used as a model protein to test the adsorption and desorption properties of the Fe3O4@C core/shell microspheres. The capacity for BHb adsorption was more than 71.3 mg/g. According to the values obtained in the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay the Fe3O4@C core/shell microspheres show a low toxicity. Therefore, the prepared Fe3O4@C core/shell microspheres are of great significance for guided site-specific drug delivery.
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Dewang Kong,Min Zhao,Shikuo Li,Fangzhi Huang,Jiming Song,Yupeng Yuan,YUHUA SHEN,ANJIAN XIE 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.1
In this paper, a facile and efficient method combined sol–gel method with hydrothermal process was employed for preparing titanium dioxide (TiO2/reduced graphene oxide (rGO) nanocomposites without using any reductants or surfactants. This approach leads to the reduction of graphene oxide (GO) and the growth of TiO2 nanorods simultaneously. The results reveal that the TiO2 short nanorods with average size of 15 nm in length and 10 nm in diameter were uniformly grown on the rGO sheets with high dispersion. Compared with the pure TiO2 nanoparticles, the TiO2/rGO composites exhibit strong absorption in the visible light range. The photocurrent density of nanocomposites reached 0.826 mA/cm2 under the simulated sunlight illumination, which is 3.5 times than that of pure TiO2. An enhancement of photocatalytic hydrogen formation rate for the water splitting was observed over the TiO2/rGO composite photocatalysts, the fastest formation rate can reach 889.28 µmol·g-1·h-1 when TiO2 coupling with 1wt.% rGO. Also the hydrogen production rate is about 3.27 times larger than pure TiO2 and 2.23 times than P25 due to the excellent electron trapping and transportation properties of rGO and the synergistic effect between TiO2 and rGO.
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