CRYSTENGCOMM
·
2020
·Vol. 22
·期 35
·5871-5881
·
IF 3.117
Zhaohui Wu,Min Wu,Zhongfu Li,Yue Pan,Junhao Qiu,Taige Li,Kaiqiang Xu,Shiying Zhang,Difa Xu,Manman Guo
In this study, the phase transition from tetragonal BiOBr to monoclinic Bi4O5Br2 was regulated in the presence of branched polyethyleneimine (BPEI) containing massive amino groups via a hydrothermal route. Based on the crystal phase of the products obtained at different concentrations of the BPEI and Br− sources, the relative concentration of BPEI (the concentration ratio of the BPEI and Br− sources, BPEI/Br−) played the decisive role in this phase transition. In particular, a BPEI/Br− value over 0.2 g mmol−1 with excessive BPEI was critical for the phase transition. Further, a reasonable theory referring the synergistic effect of the “drag force” and facet recognition of excessive BPEI underlying this phase transition was confirmed through a series of systematically designed experiments. The protonated amino groups from excessive BPEI could not only act as a “drag force” to extract the bromine ions from the solid-state BiOBr nanosheets but also recognize the (001) facet of BiOBr, thereby distorting the tetragonal structure of the BiOBr nanosheets and forming monoclinic Bi4O5Br2 nanosheets. This work provides a new insight and proof of the regulation of the phase transition of BiOBr to Bi4O5Br2.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
Scientific Reports
·
2017
·Vol. 7
·期 1
·1-9
·
IF 4.259
Liu Eryong,Li Longyang,Wang Gang,Zeng Zhixiang,Zhao Wenjie,Xue Qunji
Compliant fish skin is effectively in reducing drag, thus the design and application of compliant bionic materials may be a good choice for drag reduction. Here we consider the drag reduction of compliant bionic materials. First, ZnO and PDMS mesh modified with n-octadecane were prepared, the drag reduction of self-texturing compliant n-octadecane were studied. The results show that the mesh modified by ZnO and PDMS possess excellent lipophilic and hydrophobic, thus n-octadecane at solid, semisolid and liquid state all have good adhesion with modified mesh. The states of n-octadecane changed with temperature, thus, the surface contact angle and adhesive force all varies obviously at different state. The contact angle decreases with temperature, the adhesive force shows a lower value at semisolid state. Furthermore, the drag testing results show that the compliant n-octadecane film is more effectively in drag reduction than superhydrophobic ZnO/PDMS film, indicating that the drag reduction mechanism of n-octadecane is significantly different with superhydrophobic film. Further research shows that the water flow leads to self-texturing of semisolid state n-octadecane, which is similar with compliant fish skin. Therefore, the compliant bionic materials of semisolid state n-octadecane with regular bulge plays a major role in the drag reduction.
研究领域:
生物力学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SURFACE & COATINGS TECHNOLOGY
·
2017
·
IF 2.589
Lei Tang,Zhixiang Zeng,Gang Wang,Eryong Liu,Longyang Li,Qunji Xue
In this paper, different apertures of superhydrophilic porous TiO 2 films are fabricated by sol-gel method with PEG2000 additive. The drag reduction effect of the films is investigated through experiment of falling-ball method and FEM simulation. The larger PEG2000 content, the bigger size and the more regular and homogeneous of the pores. The joint action of anatase crystal, hydroxyl groups and water molecules absorbed on the surface and porous structure causes the superhydrophilicity. The resistance test shows that when the addition amount of PEG2000 changes from 0.25 g to 2 g, the drag reduction efficiency increases from − 17.9% to 8.6% and − 16.8% to 9.4% with 12 mm and 25 mm diameter balls. The drag reduction mechanism can be obtained from Finite Element Method simulation. The result shows that vortexes are formed in the pore which can reduce the frictional drag by lowering the velocity gradient and giving a frictional driving force. Meanwhile, an “extra press drag” is formed between the front and back wall. If the degree of friction drag reduction is greater than the degree of press drag increase, the film will show the effect of drag reduction overall.
研究领域:
材料科学
·
流体力学
✓ 已验证
DOI
高影响因子
LANGMUIR
·
2021
·
IF 3.882
Zhenyu Wang,Xiang Mao,Hua Wang,Shenggeng Wang,Zengtao Yang
This work reports a new method of fabricating lipid nanotubules using ultrasonic Stokes drag force in theory and experiment. Ultrasonic Stokes drag force generated using a planar piezoelectric ultrasonic transducer in a remotely controllable way is introduced. When ultrasonic Stokes drag force is applied on lipid vesicles, the lipid nanotubules attached can be dragged out from the lipid film. In order to demonstrate the formation mechanism of the lipid nanotubules produced by ultrasonic drag force clearly, a theoretical kinetic model is developed. In the experiments, the lipid nanotubules can be rapidly and efficiently fabricated using this ultrasonic transducer both in deionized water and NaCl solutions with different concentrations. The stretching speed of the lipid nanotubules can reach 33 μm/s, approximately 10 times faster than that of the existing methods. The formed lipid nanotubules have a diameter of 600 ± 100 nm (>80%). The length can reach the millimeter level. This work provided a remotely controllable, highly efficient, high-velocity, and solution environment-independent approach for fabricating lipid nanotubules.
研究领域:
生物物理学
·
纳米技术
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CELLULOSE
·
2020
·Vol. 27
·期 7
·4029-4041
·
IF 4.21
Wang Xiaojun,Li Runyu,Zeng Jinsong,Cheng Zheng,Wang Bin,Ding Qijun,Gao Wenhua,Chen Kefu,Xu Jun
Abstract Plant fiber isolated cellulose nanofibers (CNFs) are the materials with excellent mechanical properties. However, application of CNFs in polymer reinforcement is normally unsatisfactory due to its intertwined size distribution. Efforts to produce uniform sized CNFs have yet to be studied. In present work, spiral microchannel was used to fractionate CNFs based on the balance between inertial lift force (F L ) and Dean drag force (F D ) exerted on CNFs. The results showed that the smaller length of CNFs equilibrated near the inner microchannel while the larger length of CNFs occupied the equilibrium position away from the inner wall. With the increase of flowrates from 50 to 220 μL/min, fractionation efficiency between inner and middle outlet (E IM ) of spiral microchannel A with larger radius curvature (R) from 5 to 15 mm increased from 0 to 75.4%. However, stronger Dean flow attributing to decrease of R (3 mm to 10 mm) of single spiral microchannel B enabled satisfactory fractionation efficiency of 70.9% at flowrate of 90 μL/min. Moreover, the fractionation efficiency of double spiral microchannel with twice as length as microchannel A and three times as length as microchannel B was lower than that of single spiral microchannel at flowrate lower than 90 μL/min. Furthermore, this study exhibited a versatile and simple method for CNFs fractionation with high fractionation efficiency. Graphic abstract
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2023
·Vol. 15
·期 18
·3702
·
IF 5
Shiwei Shi,Zeshan Abbas,Xiangyu Zhao,Junsheng Liang,Dazhi Wang
To increase the printing stability of low-viscosity solutions, an auxiliary method was proposed using a coaxial electrohydrodynamic jet. A high-viscosity solution was employed as the outer layer in the printing process, and it could be removed (dissolved away) after printing the structures. A combination of mechanical and electrical forces was proposed to enhance the consistency, durability, and alignment of the printed versatile structures. The instability of the jet trajectory (which arose from the repulsion between the jet and the base with a residual charge, in addition to the winding effect of the solution) was also reduced using the drag force along the direction of movement. Moreover, the jet velocity, the surface charge, and the influence of various working voltages on the jet speed were simulated. An array of IDT-BT nanostructures measuring about 100 nm was prepared on silicon dioxide (using an inner needle with a diameter of 130 µm) by equating the moving speed (350 mm/s) of the substrate to the speed of the jet. Moreover, the moving speed (350 mm/s) of the substrate was compared exclusively to the speed of the jet. The method proposed throughout this study can provide a reference for enhancing the stability of low-viscosity solutions on substrates for high-efficiency fabrication devices (NEMS/MEMS).Keywords:CE-jet morphology;phase field model;drag;multiphysics;silicon dioxide;high-viscosity solution
研究领域:
纳米技术
·
材料科学
·
微机电系统
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
·
2021
·
IF 5.234
Dongjing Jiang,Zhi Dong,Zunfeng Du,Qian Zhao,Hui Wang,Zongqing Ma
It is an effective way to enhance the mechanical properties of Mo alloy by adding oxide strengthening phase. However, the oxide second-phase particles in oxide dispersion strengthened Mo (ODS-Mo) alloy prepared via traditional mechanical alloying generally coarsen at grain boundaries (GBs), greatly weakening their strengthening effect . To solve this problem, single and multiple oxide particles strengthened Mo alloys are developed via wet chemical method and subsequent low-temperature sintering in this work. After doping CeO 2 , the compressive yield strength (340.3 ± 8.1 MPa) and hardness (410 ± 13 HV) of Mo–Y 2 O 3 (Mo–Y) alloy were decreased by 17.9% and 22.7%, respectively. However, after doping La 2 O 3 , the compressive yield strength and hardness of Mo–Y alloy are further increased by 89.4% and 21.0%, respectively. According to microstructure observation and theoretical calculation, CeO 2 doping decreases the volume fraction of intergranular oxide particles and weakens interfacial drag force, finally promoting Mo grain growth and worsening the mechanical properties of Mo–Y alloy. In contrast, after doping La 2 O 3 , more oxide particles are dispersed at GBs, and their coarsening are inhibited. This results in a stronger Zener force. Moreover, interfacial drag force can also be increased through doping La 2 O 3 . Two forces synergistically hinder GBs migration. Therefore, La 2 O 3 doping leads to Mo grain refinement and ultimately enhances the mechanical properties of Mo–Y alloy. These results in our work can provide theoretical guidance for choosing proper oxide dopants to prepare ODS alloys with excellent mechanical properties.
研究领域:
材料科学
·
金属学与热处理
·
结构材料
·
粉末冶金
·
固态相变
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）