Facile Fabrication of Flame-retardant SiO2/APP@PDMS Fabric with Superhydrophobicity for Highly Efficient Oil/Water Separation

Weijing Zhao,Xinyan Xiao,Zhihao Ye 한국섬유공학회 2021 Fibers and polymers Vol.22 No.2

Flame-retardant SiO2/APP@PDMS fabric with superhydrophobicity was prepared via ultrasound-assisted sol-gelmethod and dip-coatings, in which cotton fabric was substantially decorated with amino functionalized SiO2 (SiO2-NH2),ammonium polyphosphate (APP) and polydimethylsiloxane (PDMS). The surface morphology, element composition andfunctional groups were examined by SEM, EDS and ATR-FTIR, respectively. The SiO2/APP@PDMS fabric exhibited selfcleaningproperty to the solid and liquids with water contact angle (WCA) around 154 °, and showed high separationefficiency for n-dodecane (98.5 %) and n-hexane (96 %), which maintained stable after 10 separation cycles. Furthermore,the SiO2/APP@PDMS fabric presented a lower mass loss rate from TGA curve, indicating the improved thermal stability. The synergistic effect of PDMS and APP resulted in the excellent flame-retardant property of the SiO2/APP@PDMS fabric,during which the dense intumescent char layer formed and the fabric extinguished immediately. The SiO2/APP@PDMSfabric with facile fabrication process exhibited potential applications for both oil/water separation and flame-retardant areas.

The Application of Visual Languages in New Media Art

Weijing Wei,Teayong Kim 중앙대학교 영상콘텐츠융합연구소 2019 TechArt :Journal of Arts and Imaging Science Vol.6 No.1

Static Stability Analysis of Single-Layer Reticulated Spherical Shell with Kiewitt-Sunflower Type

Peng Yu,Weijing Yun,Stéphane Bordas,Sheng He,Yiming Zhou 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.5

In this study, we use a large-scale parameter analysis and linear regression method to characterize the static stability of Kiewitt-sunfl ower-type single-layer reticulated spherical shell. Based on more than 15,000 numerical cases of elastic–plastic load–displacement process, and the investigations on the infl uence of buckling and instability mode, rise-span and ringnumbers ratio, effi ciency of the structure, load distribution, support conditions, size of the initial geometric imperfection and distribution patterns are proceeded. We summarize the key eff ect for stable performance of structure, and develop the formulation to calculate the ultimate capacity of stability. The results show that Kiewitt-sunfl ower type single-layer reticulated spherical shell is sensitive to defect, and diff erent distribution patterns of geometry defect lead to diff erent structural buckling. The ultimate stability bearing capacity can be improved by increasing the rise-span and ring-numbers ratio. The asymmetrical load distribution has little eff ect on the stability. The most unfavorable eigenmode is arbitrary, and it is generally not the lowest order. We summarize the key eff ect for stable performance of structure, and develop the formulation to calculate the ultimate capacity of stability.

Massive MIMO Channel Estimation Algorithm Based on Weighted Compressed Sensing

Zhiguo Lv,Weijing Wang 한국정보처리학회 2021 Journal of information processing systems Vol.17 No.6

Compressed sensing-based matching pursuit algorithms can estimate the sparse channel of massive multiple input multiple-output systems with short pilot sequences. Although they have the advantages of low computational complexity and low pilot overhead, their accuracy remains insufficient. Simply multiplying the weight value and the estimated channel obtained in different iterations can only improve the accuracy of channel estimation under conditions of low signal-to-noise ratio (SNR), whereas it degrades accuracy under conditions of high SNR. To address this issue, an improved weighted matching pursuit algorithm is proposed, which obtains a suitable weight value uop by training the channel data. The step of the weight value increasing with successive iterations is calculated according to the sparsity of the channel and uop. Adjusting the weight value adaptively over the iterations can further improve the accuracy of estimation. The results of simulationsconducted to evaluate the proposed algorithm show that it exhibits improved performance in terms of accuracy compared to previous methods under conditions of both high and low SNR.

Numerical analysis of stress wave of projectile impact composite laminate

Zhangxin Guo,Weijing Niu,Junjie Cui,Gin Boay Chai,Yongcun Li,Xiaodong Wu 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.87 No.2

The three-dimensional Hashin criterion and user subroutine VUMAT were used to simulate the damage in the composite layer, and the secondary stress criterion was used to simulate the interlayer failure of the cohesive element of the bonding layer and the propagation characteristics under the layer. The results showed that when the shear stress wave (shear wave) propagates on the surface of the laminate, the stress wave attenuation along the fiber strength direction is small, and thus producing a large stress profile. When the compressive stress wave (longitudinal wave) is transmitted between the layers, it is reflected immediately instead of being transmitted immediately. This phenomenon occurs only when the energy has accumulated to a certain degree between the layers. The transmission of longitudinal waves is related to the thickness and the layer orientation. Along the symmetry across the thickness direction, the greater is the stress amplitude along the layer direction. Based on the detailed investigation on the impact on various laminated composites carried out in this paper, the propagation characteristics of stress waves, the damage and the destruction of laminates can be explained from the perspective of stress waves and a reasonable layering sequence of the composite can be designed against damage and failure from low velocity impact.

Schisantherin A Improves Learning and Memory of Mice with D-Galactose-Induced Learning and Memory Impairment Through Its Antioxidation and Regulation of p19/p53/p21/ Cyclin D1/CDK4/RB Gene Expressions

Cong Liu,Weijing Sun,Ning Li,Jiaqi Gao,Chunyan Yu,Chunmei Wang,Jinghui Sun,Shu Jing,JianGuang Chen,He Li 한국식품영양과학회 2018 Journal of medicinal food Vol.21 No.7

Schisantherin A (SCA) was evaluated for possible function in restoring the learning and memory impairment induced by D-galactose in mice. ICR mice were treated with D-galactose subcutaneously (220 mg·kg−1), and followed by SCA in different doses (1.25, 2.50 and 5.00 mg·kg−1, administered orally) for 42 days. Effects of SCA on learning and memory were examined by step-through tests and Morris water maze tests. The activity of superoxide dismutase (SOD), the content of malondialdehyde (MDA) in the peripheral blood and hippocampus of mice were assayed by water-soluble tetrazolium-1 (WST-1) and thiobarbituric acid (TBA) methods. The contents of 8 hydroxy deoxy guanosine (8-OHdG) in the hippocampus of mice were detected by immunosorbent assay methods, respectively. Quantitative real-time PCR and Western Blot were respectively used to detect the expression of p19, p53, p21, cyclin D1, CDK4 and RB genes, and the phosphorylation of RB in the hippocampus of mice. We found that SCA significantly improved the learning and memory impairment induced by D-galactose in mice. After SCA treatment, SOD activity was increased and the content of MDA was decreased in both peripheral blood and hippocampus of mice. 8-OHDG content was also decreased in the hippocampus of mice. Furthermore, the expression of p19, p53 and p21 genes was reduced and the expression of cyclin D1 and CDK4 and the phosphorylation of RB protein were elevated in the hippocampus. SCA may improve the learning and memory impairment induced by D-galactose by enhancing the antioxidant capacity, and regulating the expression of p19/p53/p21/cyclinD1/CDK4 genes, and the phosphorylation of RB protein in the hippocampus of mice.

A study of the corrosion resistance of a micro-arc oxidation coating on a cast aluminum-copper alloy

Shihai Cui,Jianmin Han,Weijing Li,Xiangyang Xu,Yuanfu Liu 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.4

Protective coatings have been successfully prepared on a high strength aluminum-copper alloy ZL205 using a micro-arc oxidation (MAO) method. The influence of the oxidation time and current density on the thickness and corrosion resistance of MAO coatings has been studied. The thickness of MAO coating increases linearly with an increase of oxidation time. When the oxidation time is shorter than 20 minutes, the coating improves the corrosion resistance of ZL205 alloy quickly with an increase of oxidation time, which is confirmed by 5% salt spray test. When the oxidation time is longer than 20 minutes, the corrosion resistance of the MAO coating increases slowly with an increase of oxidation time. For a fixed oxidation time, the thickness of the MAO coating increases with an increase of current density and the corrosion resistance can also be improved. SEM and XRD analysis show that the surface morphology and phase of the MAO coating change with an increase of the oxidation time, which results in different corrosion resistance of the MAO coating. Protective coatings have been successfully prepared on a high strength aluminum-copper alloy ZL205 using a micro-arc oxidation (MAO) method. The influence of the oxidation time and current density on the thickness and corrosion resistance of MAO coatings has been studied. The thickness of MAO coating increases linearly with an increase of oxidation time. When the oxidation time is shorter than 20 minutes, the coating improves the corrosion resistance of ZL205 alloy quickly with an increase of oxidation time, which is confirmed by 5% salt spray test. When the oxidation time is longer than 20 minutes, the corrosion resistance of the MAO coating increases slowly with an increase of oxidation time. For a fixed oxidation time, the thickness of the MAO coating increases with an increase of current density and the corrosion resistance can also be improved. SEM and XRD analysis show that the surface morphology and phase of the MAO coating change with an increase of the oxidation time, which results in different corrosion resistance of the MAO coating.

The microstructure and corrosion resistance of micro-arc oxidation coatings on SiCp/A356 composites

Shihai Cui,Jianmin Han,Weijing Li,강석봉,이정무 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.4

Micro-arc oxidation (MAO) coatings were prepared on a SiCp/A356 composite. The microstructure and phase composition of the coatings on the SiCp/A356 composite were examined by XRD and SEM methods. It was found that there were two layers in the coating, a dense layer which was mainly composed of crystalline α-Al2O3 and a loose layer which consisted of γ-Al2O3 and mullite. The coating was well bonded to the SiCp/A356 substrate. The corrosion behavior of the coated and uncoated SiCp/ A356 composites was evaluated with a salt spray test and a potentiodynamic polarization technique. The results of the salt spray test showed that the coating could improve the corrosion resistance of SiCp/A356 by 11 times. The corrosion potential was shifted significantly in the anodic direction and the corrosion current density of the coated SiCp/A356 composite was reduced.

Seismic Performance of Kiewitt-Sunflower Single Layer Spherical Reticulated Shells

Sheng He,Siliu Yu,Weijing Yun,Stéphane P. A. Bordas,Peng Yu 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.5

In this paper, seismic behavior of Kiewitt-Sunflower single layer spherical reticulated shells is examined within the time history method, based on our proposed damage constitutive model for thin-walled circular steel tubes. According to a large number of numerical examples, the failure mode of this kind of single layer spherical reticulated shell in the case of earthquake is figured out. In addition, the effect of the damage accumulation, rise-span ratio, initial geometric imperfection, types of seismic wave and amplitude modulation ratio on the dynamic response of the shell structure is explored. Finally, a structural damage factor is proposed and it has a good match with the numerical results, which is productive to assess the damage and failure behavior of such structures suffering the earthquake and post-earthquake.

Porous Nano-Ni/Graphene/Loofah Composites for Electromagnetic Interference Shielding

Yi Jiang,Mingwei Liang,Weijing Wang,Xuefei Lai,Kenan Xie,Li Liao,Qin Long 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.4

The urgent requirement of materials with superior electromagnetic shielding properties has been aroused for alleviating electromagnetic pollution. Now, some natural materials such as silkworm cocoon, walnut shell, and so on are gradually used to prepare the electromagnetic interference shielding composites. However, loofah sponges with unique and inherent 3D hierarchical porous structure, which could be obtained from food waste and the wilted loofah, are ignored. In this work, loofah sponges were modified by NaOH and H2 O2 . Then the carbonized modified Loofah/Ni nanoparticles/Graphene composites were prepared by immersion and thermal reduction. Meanwhile, the composites had inherited advantages from natural materials such as low density, porous structure and eco-friendly. As the result of loading of Ni nanoparticles and graphene on the loofah, the outstanding performance was achieved that the shielding effectiveness was raised to 57 dB, and the specific shielding effectiveness was raised to 616.8 dB cm 3 /g. This result demonstrated that composites materials based on natural loofah sponges show tremendous potential for electromagnetic shielding.