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Biosorption of Lead(II) by Arthrobacter sp. 25: Process Optimization and Mechanism
( Yu Jin ),( Xin Wang ),( Tingting Zang ),( Yang Hu ),( Xiaojing Hu ),( Guangming Ren ),( Xiuhong Xu ),( Juanjuan Qu ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.8
In the present work, Arthrobacter sp. 25, a lead-tolerant bacterium, was assayed to remove lead(II) from aqueous solution. The biosorption process was optimized by response surface methodology (RSM) based on the Box-Behnken design. The relationships between dependent and independent variables were quantitatively determined by second-order polynomial equation and 3D response surface plots. The biosorption mechanism was explored by characterization of the biosorbent before and after biosorption using atomic force microscopy (AFM), scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The results showed that the maximum adsorption capacity of 9.6 mg/g was obtained at the initial lead ion concentration of 108.79 mg/l, pH value of 5.75, and biosorbent dosage of 9.9 g/l (fresh weight), which was close to the theoretically expected value of 9.88 mg/g. Arthrobacter sp. 25 is an ellipsoidalshaped bacterium covered with extracellular polymeric substances. The biosorption mechanism involved physical adsorption and microprecipitation as well as ion exchange, and functional groups such as phosphoryl, hydroxyl, amino, amide, carbonyl, and phosphate groups played vital roles in adsorption. The results indicate that Arthrobacter sp. 25 may be potentially used as a biosorbent for low-concentration lead(II) removal from wastewater.
Guangming Zheng,Zhenying Huang,Qun Yu,Wenqiang Hu,Xingyang Qiu,A. Lixia,Yuanbo Wang,Yidan Jiao,Yang Zhou,Hongxiang Zhai 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.6
In this paper, a novel type of functionally graded material (FGM) was successfully fabricated from pure Ni and Ti3AlC2powder mixtures by hot-press sintering route at 1200 °C and 17 MPa. In each layer, Ti3AlC2particles transformed into TiCxphase, while the additional Al–Ti atoms decomposed from Ti3AlC2diffused into the Ni matrix, giving rise to the formationof γ′-Ni3(Al,Ti). Part of the submicron TiCxand Ni3(Al,Ti) particles were uniformly distributed in the Ni matrix, whilesome of the TiCxmaintained the original Ti3AlC2plate-like morphology. Both TiCxand Ni3(Al,Ti) content decreased from60Ti3AlC2/Ni layer to 10Ti3AlC2/Ni layer in a stepwise manner was fabricated. The microstructural analysis indicatesthat no cracks, delamination and step-type abrupt changes occured in the graded layer of the manufactured FGM. Flexuralstrength and Vickers hardness enhanced with the increasing Ti3AlC2content except for fracture strain and toughness. Theoverall fracture toughness and the flexural strength of FGM can reach 21.76 MPa m1/2 and 1329 ± 34 MPa, respectively. Theprepared FGM, herein, with a hard ceramic surface on one side to resist local plastic deformation, and a ductile metallicsurface on the other side to provide toughness.
Stiffness effects on repeatability of positioning of linear axes
Guangming Sun,Yimiao Wang,Wenjin Wang,Jinjun Liu,Ming Yu,Jian Zhao 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.9
This paper studies the effect of stiffness (including slider stiffness and bearing stiffness) on the repeatability of the positioning of linear axes. First, a mathematical model between stiffness and the repeatability of the positioning of linear axes is established. The effects of the stiffness of the slider and bearing on the repeatability of positioning are analysed. The theoretical results show that the repeatability of the positioning decreases as the slider component stiffness and bearing stiffness increases. Second, a finite element analysis is implemented to calculate the effect of slider stiffness on the repeatability of positioning, the simulation results are found to be consistent with the theoretical results. Finally, the effect of bearing stiffness on the repeatability of positioning is experimentally investigated. The experimental and theoretical analysis results have been observed to coincide. Thus, the accuracy of the theoretical analysis is verified by both simulation and experimental results. The derived results afford designers and engineers a scientific basis for the stiffness design theory.
Thermal Shock Behavior of a Novel TiCx–Ni3(Al,Ti)/Ni Functionally Graded Composite
Qun Yu,Zhenying Huang,Guangming Zheng,Wenqiang Hu,Cong Lei,Yuanbo Wang,Yidan Jiao,Hongxiang Zhai 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.12
This paper focuses on the study of thermal shock behaviors of a novel TiCx–Ni3(Al,Ti)/Ni functionally graded material (FGM)fabricated from Ti3AlC2and Ni powders. Thermal shock resistance of resulted FGM was conducted by water quenching atdifferent temperatures, mechanical properties and microstructures after thermal shocks were correspondingly determined andcharacterized. The microstructure of the FGM after thermal shocks shows no cracks of instability failure between the transitionzones, and the reinforcement phases were closely combined with the matrix. Meanwhile, compared with the strengthof 1329 MPa without thermal shock, when the temperature of the thermal shock reached 800 °C and 1000 °C respectively,with 10 repeated heat-water quench cycles, the residual flexural strength of FGM decreased slightly, but it could still reach1100 MPa. Notably, the strength can still maintain at 843 MPa after 10 cycles of thermal shock at 1200 °C. Such excellentthermal shock performance may be the result of the good interfacial bonding and the special gradient structure, the oxidationlayer also plays a protective role.
Qi Yang,Yu Zhong,Xiaoming Li,Xin Li,Kun Luo,Xiuqiong Wu,Hongbo Chen,Yang Liu,Guangming Zeng 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.28 No.-
In this study, the bromate removal was investigated in continuous fixed-bed column using Fe(II)–Al(III)layered double hydroxide (LDH). With increase of column bed depth from 1.0 to 3.0 cm, breakpoint time(tb) increased from 51 to 175 h while throughput volume raised from 12.24 to 42.00 L at breakthroughpoint. The bromate removal was attributed to the reduction of Fe(II) present in LDH. The breakthroughcurve was simulated well by Thomas model, but BDST model was the only effective to initial part(1–10%). The maximum removal capacity (N0) calculated by Thomas model reached 71.01 mmol/g atflow rate (3 mL/min).
Zhiliang Liu,Liang Li,Guangming Yu,Jun Hu,Houlai Lin,Chunli Li,Shibao Lu,Kaiqi Meng,Jun Lei 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.2
A method of calculating the failure probability of the tunnel system combining finite element numerical simulation with multiple response surface method (MRSM) and Monte-Carlo simulation (MCS) is presented. The applicability of the proposed methodology is verified through a subway interval soft rock tunnel in Qingdao, China. The sensitivity of Monte-Carlo sampling number and coefficients of variation for rock masses on the failure probability of tunnel system is conducted. The primary failure modes in tunnel system are identified by reanalyzing the failure samples. The simulation results demonstrate that the failure probability of a tunnel system within soft upper and hard lower surrounding rock mass is mainly attributed to the soft upper part of the surrounding rock. The coefficients of variation of the elastic modulus E1 and the internal friction angle ϕ1 of the pebble layer (soft upper part) have significant effect on the failure probability. The failure probability of tunnel system increases as the coefficients of variation of E1 and ϕ1 increase. Two primary failure modes are found to contribute to the tunnel system reliability. The effect of rock bolt length L and pipe-roof thickness H on tunnel system reliability and two primary failure modes as well are investigated. The simulation results indicate that both the enhancements in L and H tend to be more effective than the enhancement in either L or H if a small target failure probability of tunnel system is expected. The supporting structures design can be performed based on the potential sets of (L, H) satisfying target failure probability.
Second-Order Consensus of Multi-Agent Systems with Unknown but Bounded Disturbance
Hongxiang Hu,Li Yu,Guang Chen,Guangming Xie 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.2
This paper addresses a consensus problem for second-order agents with unknown but bounded (UBB for short) disturbance which may affect the measure of neighbors’ velocities. In this study, the communication topology of the multi-agent system is supposed to be connected. In order to solve this consensus problem, a new velocity estimation called distributed lazy rule is firstly proposed, where each agent can estimate its neighbors’ velocities one by one. Then, a group of sufficient conditions for this second-order consensus problem are presented by adopting graph theory and the well-known Barbalat lemma, and the bounded consensus protocol is taken into account due to actuator saturation. Theoretically, the group of agents can reach consensus under the proposed control protocol, which is also validated by some numerical experiments.
Zhao Linjie,Yang Mao,Xiao Chengjian,Gong Yu,Ran Guangming,Chen Xiaojun,Li Jiamao,Yue Lei,Chen Chao,Hou Jingwei,Wang Heyi,Long Xinggui,Peng Shuming 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.1
Understanding the tritium release and retention behavior of candidate tritium breeder materials is crucial for breeder blanket design. Recently, a melt spraying process was developed to prepare Li4SiO4 pebbles, which were subsequently subjected to the in-pile tritium production and extraction platform in China Mianyang Research Reactor (CMRR) to investigate their in-situ tritium release behavior and irradiation performance. The results demonstrate that HT is the main tritium release form, and adding hydrogen to the purge gas reduces tritium retention while increasing the HT percent in the purge gas. Post-irradiation experiments reveal that the irradiated pebbles darken in color and their grains swell, but the mechanical properties remain largely unchanged. It is concluded that the tritium residence time of Li4SiO4 made by melt spraying method at 467 ◦C is approximately 23.34 h. High-density Li4SiO4 pebbles exhibit tritium release at relatively low temperatures (<600 ◦C) that is mainly controlled by bulk diffusion. The diffusion coefficient at 525 ◦C and 550 ◦C is 1.19 × 10 11 cm2/s and 5.34 × 10 11 cm2/s, respectively, with corresponding tritium residence times of 21.3 hours and 4.7 hours.