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Xue Li,아떼크아메드,최병상 대한금속·재료학회 2021 대한금속·재료학회지 Vol.59 No.11
A three-dimensionally interconnected graphene-reinforced Cu (3Di Gr-Cu) composite was synthesized using a simple two-step process technique which involves the mechanical compaction of micronsized Cu particles followed by chemical vapor deposition (CVD) at 995 oC. The microstructural properties of pure Cu and the 3Di Gr-Cu composite were investigated by optical microscope, scanning electron microscope, and X-ray diffractometer. The electrical and corrosion behaviors of the 3Di Gr-Cu composite and Cu only, prepared by powder metallurgy (PM Cu), were studied and compared. The electrical conductivity (EC) of the 3Di Gr-Cu composites was found to be 38.8 MSm−1 at a carbon content of 73 ppm, and exhibited a 12% higher EC than the PM Cu. Due to the interconnected graphene around the Cu grains, the corrosion current density and corrosion rate of the 3Di Gr-Cu composite decreased by 29% and 40%, respectively, compared to the PM Cu. The EC of the 3Di Gr-Cu composite depended on the carbon content. The improvement in the EC of the 3Di Gr-Cu composite is attributed to the electron-carrying ability of the three-dimensionally interconnected graphene network (3DIGN) formed at the grain boundaries in the composite. The enhancement in corrosion resistance is due to the impermeability of graphene to various chemical species.
Xue Li,Xueer Chen,Yikang Yang,Lipo Mo 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.2
This paper studies consensus problems of high-order heterogeneous continuous-time networks with bounded communication delays and dynamically changing digraphs. The heterogeneous continuous-time networks consist of different order agents from first-order to lth-order agents, where different order networks correspond to different linear consensus protocols. In order to use the properties of Metzler matrix with zero row sums, we make model transformations of system matrix. Giving some restrictive conditions, we obtain the sufficient condition for consensus problems of heterogeneous networks with varying bounded communication delays. Although each communication graph may have no spanning trees, all agents of high-order heterogeneous networks can reach stationary consensus with varying bounded communication delays and dynamically changing digraphs. Finally, we give an example to validate the correctness of our obtained results.
Xue Li,Terry Arthur Ring,최병상 대한금속·재료학회 2019 대한금속·재료학회지 Vol.57 No.8
A Cu composite reinforced by a three-dimensionally interconnected graphene network was synthesized in situ by a simple two-step process utilizing compacted Cu powder (99% purity) as a template for the growth of graphene. Cu composites with different graphene contents were obtained by controlling the processing parameters. The composites were approximated to have two layers of graphene with curved shapes, high aspect ratios, and which were wrapped around Cu grains at the grain boundaries. The threedimensionally interconnected graphene structure formed throughout the Cu matrix can act as a barrier to Cu diffusion and dislocation movement. Enhanced thermal conductivities (TCs) of 406 ± 5 W/mK and 385 ± 7 W/mK in the through- and in-plane directions, respectively, were obtained at room temperature for the Cu composite with a disc density of 8.16 g/cm3 and carbon content of ~ 73 ppm. The lower in-plane TC as compared to the through-plane TC could be explained by the increased number of defects as the measurement distance increased from 0.9 mm (through-plane) to 13 mm (in-plane). In conclusion, the spatial distribution of the three-dimensionally interconnected continuous graphene network throughout the Cu matrix must provide effective pathways for thermal conduction in the Cu composite, to thereby enable relatively high thermal conduction.
Xue Li,Jun Fu,Martin Steinhart,김동하,Wolfgang Knoll 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.6
A simple approach to prepare arrays of Au/TiO2 composite nanoparticles by using Au-loaded block copolymers as templates combined with a sol-gel process is described. The organic-inorganic hybrid films with closely packed inorganic nanodomains in organic matrix are produced by spin coating the mixtures of polystyrene-block-poly(ethylene oxide) (PS-b-PEO)/HAuCl4 solution and sol-gel precursor solution. After removal of the organic matrix with deep UV irradiation, arrays of Au?/?TiO2 composite nanoparticles with different compositions or particle sizes can be easily produced. Different photoluminescence (PL) emission spectra from an organic-inorganic hybrid film and arrays of Au/TiO2 composite nanoparticles indicate that TiO2 and Au components exist as separate state in the initial hybrid film and form composite nanoparticles after the removal of the block copolymer matrix.
( Xue Li ),( Yan-hua Liu ),( Xin Zhang ),( Chang-ming Ge ),( Ren-zhe Piao ),( Wei-dong Wang ),( Zong-jun Cui ),( Hong-yan Zhao ) 한국미생물 · 생명공학회 2017 Journal of microbiology and biotechnology Vol.27 No.3
The development and utilization of crop straw biogas resources can effectively alleviate the shortage of energy, environmental pollution, and other issues. This study performed a continuous batch test at 35°C to assess the methane production potential and volatile organic acid contents using the modified Gompertz equation. Illumina MiSeq platform sequencing, which is a sequencing method based on sequencing-by-synthesis, was used to compare the archaeal community diversity, and denaturing gradient gel electrophoresis (DGGE) was used to analyze the bacterial community diversity in rice straw, dry maize straw, silage maize straw, and tobacco straw. The results showed that cumulative gas production values for silage maize straw, rice straw, dry maize straw, and tobacco straw were 4,870, 4,032.5, 3,907.5, and 3,628.3 ml/g ·VS , respectively, after 24 days. Maximum daily gas production values of silage maize straw and rice straw were 1,025 and 904.17 ml/g ·VS, respectively, followed by tobacco straw and dry maize straw. The methane content of all four kinds of straws was > 60%, particularly that of silage maize straw, which peaked at 67.3%. Biogas production from the four kinds of straw was in the order silage maize straw > rice straw > dry maize straw > tobacco straw, and the values were 1,166.7, 1,048.4, 890, and 637.4 ml/g ·VS, respectively. The microbial community analysis showed that metabolism was mainly carried out by acetateutilizing methanogens, and that Methanosarcina was the dominant archaeal genus in the four kinds of straw, and the DGGE bands belonged to the phyla Firmicutes, Bacteroidetes, and Chloroflexi. Silage maize is useful for biogas production because it contains four kinds of straw.
Synthesis of Co-doped micro-mesoporous SAPO-11 zeolite for glycerol hydrogenolysis
Xue Li,Dongfang Wu 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.2
Co-doped micro-mesoporous SAPO-11 zeolite (Co-MSAPO-11) was synthesized and used for hydrogenolysis of glycerol. After simultaneous introduction of Co and mesopores, the pore structure and acidic properties of microporous SAPO-11 zeolite are reintegrated. The larger mesopores of Co-MSAPO-11 facilitate the diffusion of molecules and provide more space for the highly dispersed Co species. The appropriate acidity of Co-MSAPO-11 with more Lewis acid sites appears to be more helpful for the activation of reactants to intermediates, potentially increasing the probability of high selectivity to 1,2-propanediol. Therefore, Co-MSAPO-11 shows unique catalytic performance with a glycerol conversion of 94.0% and selectivity to 1,2-PDO of 90.5% under mild conditions. The possible representative model of Co-MSAPO-11 is proposed for the first time.
Xue Li,Tingting Liu,Fei Tian,Xiyang Tao,Zhansheng Wu 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.11
The high cost and low carrier separation efficiency of g-C3N4/Ag2O photocatalysts affect its application in the degradation of organic pollutants. In this study, the CA-βCD/g-C3N4/Ag2O 2D/0D heterojunction photocatalysts were successfully prepared to enhance the visible light response and inhibit the electron-hole recombination simultaneously during pollutant degradation. The 10:1:1 CA-βCD/g-C3N4/Ag2O showed the outstanding photochemical catalysis performance for the degradation of organic pollutants. The degradation efficiency of methyl orange, reactive black and norfloxacin was 2.53, 1.92 and 1.14 times than that of 1:1 g-C3N4/Ag2O. In addition, 10:1:1 CA-β-CD/g-C3N4/Ag2O also showed excellent photocatalytic stability. The free radical scavenging experiment and electron spin resonance proved that ·O − 2 was the chief active specie in the degradation process. The mechanism research results showed that the formation of heterojunction improved the utilization rate of sunlight and promoted the separation efficiency of photo-generated electrons and holes, which significantly advanced the photocatalytic activity of the composite catalyst. The preparation of CA-βCD/g-C3N4/Ag2O provided ideas for modification of photocatalyst by macromolecular organic matter.
Prediction Model for the Teeth Hob Cutter of Tunnel Boring Machines in High-content Quartzite Strata
Xue Li,Jiuqi Wu,Peng Huo 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.1
Teeth hob cutter is widely used in cutting through hard rock. Cutter wear is inevitable during the strata with a large quartzite content, and excessive wear can lead to a decrease in tunneling efficiency and increase construction risks. Therefore, the importance of predicting the teeth hob cutter wear accurately and arranging the cutter change plan can never be overemphasized. In this paper, the rock breaking mechanism of teeth hob cutter was first analyzed. Based on this, combined with the theory of metal tribology theory, the wear prediction model for teeth hob cutters in high-content quartzite strata was derived. To verify the accuracy of the prediction model, the teeth hob cutter wear data for two cases were measured, which were collected from a cross-river shield tunnel project in Guangdong, China. Based on the observed wear data, it is found that the relative error of predicted wear and actual measurement was below 10%. The result shows that the prediction model can accurately reflect the real wear situation of teeth hob cutter in high-content quartzite strata.