| 1. |
- Zhou, Yali, et al.
(författare)
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Long-Term Stability of Different Kinds of Gas Nanobubbles in Deionized and Salt Water
- 2021
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Ingår i: Materials. - : MDPI. - 1996-1944 .- 1996-1944. ; 14:7
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Tidskriftsartikel (refereegranskat)abstract
- Nanobubbles have many potential applications depending on their types. The long-term stability of different gas nanobubbles is necessary to be studied considering their applications. In the present study, five kinds of nanobubbles (N2, O2, Ar + 8%H2, air and CO2) in deionized water and a salt aqueous solution were prepared by the hydrodynamic cavitation method. The mean size and zeta potential of the nanobubbles were measured by a light scattering system, while the pH and Eh of the nanobubble suspensions were measured as a function of time. The nanobubble stability was predicted and discussed by the total potential energies between two bubbles by the extended Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. The nanobubbles, except CO2, in deionized water showed a long-term stability for 60 days, while they were not stable in the 1 mM (milli mol/L) salt aqueous solution. During the 60 days, the bubble size gradually increased and decreased in deionized water. This size change was discussed by the Ostwald ripening effect coupled with the bubble interaction evaluated by the extended DLVO theory. On the other hand, CO2 nanobubbles in deionized water were not stable and disappeared after 5 days, while the CO2 nanobubbles in 1 mM of NaCl and CaCl2 aqueous solution became stable for 2 weeks. The floating and disappearing phenomena of nanobubbles were estimated and discussed by calculating the relationship between the terminal velocity of the floating bubble and bubble size.
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| 2. |
- Gao, Qingwei, et al.
(författare)
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Preliminary study on mechanism of confined mass transfer and separation : "secondary confinement" effect of interfacial adsorption layer [限域传质分离机制初探:界面吸附层的"二次限域"效应]
- 2020
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Ingår i: Huagong Xuebao/CIESC Journal. - : Materials China. - 0438-1157. ; 71:10, s. 4688-4695
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Tidskriftsartikel (refereegranskat)abstract
- The confined mass transfer separation membrane is mainly for the high-precision separation process at the molecular/ion level, which is of great significance to solve the application needs of CO2 separation, azeotrope separation, lithium extraction from salt lake, desalination of seawater and so on. However, at present, the research of the confined mass transfer mechanism of this kind of membrane is lagging behind, and the theoretical models of confined mass transfer are lacking, which can no longer meet the needs of the rapid development of materials and chemical engineering. From the perspective of meso-science, the abnormal phenomenon of high flux and high selectivity of the confined mass transfer separation membrane is considered, that is, breaking through the trade-off effect, which is governed by compromise-in-competition between the selectivity mechanism and the flux mechanism. It is found that the fluid molecules will preferentially adsorb at the interface and form a stable adsorption layer. Based on this, the hypothesis of "secondary confinement" is put forward, that is, the surface induced new solid-like interface will have confinement effect on the intermediate fluid again. By comparing the pore size and the secondary confined size of the confined mass transfer separation membrane, the selective mechanism of the secondary confinement is further confirmed, and the quantitative prediction of the membrane flux and selectivity is preliminarily explored by combining the selective mechanism and the flux model, which may provide a theoretical basis for the precise construction of the limited area mass transfer membrane. © 2020, Chemical Industry Press Co., Ltd. All right reserved.
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| 3. |
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| 4. |
- Qin, Congwen, et al.
(författare)
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Insight into the Keratin Ratio Effect of the Keratin/Cellulose Composite Fiber
- 2024
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Ingår i: ACS Applied Polymer Materials. - : American Chemical Society. - 2637-6105. ; 6:1, s. 265-276
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Tidskriftsartikel (refereegranskat)abstract
- In this work, biocompatible composite fibers were prepared from human hair keratin and plant cellulose with different proportions by the wet-spinning method, and their properties and performance, including chemical structures, morphology, mechanical strength, and cell proliferation and attachment, were systematically investigated. It showed that the best proportion of the keratin/cellulose mass ratio was 30:70, and its tensile strength reached 277 MPa (elongation at break can be 27%), which is higher than that of the regenerated cellulose fiber (193 MPa, 12%). Its viability and proliferation of L929 murine fibroblast cells are also better than those of the regenerated cellulose fiber. Atomistic simulations were carried out and demonstrated the formation of hydrogen bonds between keratin and cellulose molecules, clarifying that the ratio of keratin has a significant effect on the aggregation structures in the solution and that the hydrogen bonds formed between keratin and cellulose molecules have a distinct contribution to the biocompatible composites. This work demonstrates the potential of the prepared composite fiber in biomedical applications and provides an innovative way to utilize waste human hair as a high-value raw material.
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| 5. |
- Qin, Yao, et al.
(författare)
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Atomistic insight into the lubrication of glycerol aqueous solution: The role of the solid interface-induced microstructure of fluid molecules
- 2022
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Ingår i: AIChE Journal. - : John Wiley & Sons. - 0001-1541 .- 1547-5905. ; 68:4
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Tidskriftsartikel (refereegranskat)abstract
- Molecular dynamics simulations are performed to investigate the solid surface-induced microstructure and friction coefficient of glycerol aqueous solutions with different water contents confined in graphene and FeO nanoslits. Results show that the friction coefficient of glycerol aqueous solutions confined in both nanoslits presents similar nonlinear variation tendencies with increasing water content, but their lowest value and the corresponding water contents differ. Distinctive microstructures of the near-surface liquid layer induced by surfaces with different hydrophilicity are responsible for their difference in lubrication. The sliding primarily occurs at the solid–liquid interface for the hydrophobic graphene nanoslit owing to almost the same velocity difference in fluid molecules. By contrast, the sliding mainly occurs at the liquid–liquid interface for the hydrophilic FeO nanoslit because of the large velocity difference in fluid molecules. The weaker the interaction force at the sliding position, the lower the friction coefficient.
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| 6. |
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| 7. |
- Zhang, Yumeng, et al.
(författare)
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Molecular insight into flow resistance of choline chloride/urea confined in ionic model nanoslits
- 2021
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Ingår i: Fluid Phase Equilibria. - : Elsevier. - 0378-3812 .- 1879-0224. ; 533
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Tidskriftsartikel (refereegranskat)abstract
- Choline chloride/urea (1:2) is the most widely used deep eutectic solvent, which has attracted much attention due to its excellent advantages of low cost, environment friendly and easy synthesis. In this work, nanofriction-based molecular dynamics simulations were performed to investigate the effect of interfacial hydrophilicity on the flow resistance of Choline chloride/urea (1:2) confined in ionic model nanoslits. Simulation results showed that the flow resistance of the choline chloride/urea system increases with the increasing interfacial hydrophilicity. Urea molecules form a preferential adsorption layer on the wall. As the interfacial hydrophilicity increases, the number of urea molecules in the interfacial adsorption layer increased, whereas the stability decreased. Unique confined spatial distributions of urea molecules greatly contribute to ionic association between choline cations and chloride anions. Furthermore, with the increase of interfacial hydrophilicity, orientation distributions of urea molecules in the adsorption layer are more orderly, then causing a decrease in the average hydrogen bond number (NHB) of urea molecules. Moreover, the more the NHB of urea molecules, the better is the stability in the interfacial adsorption layer, which in turn results in less flow resistance.
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| 8. |
- Zhang, Yumeng, et al.
(författare)
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Progress in molecular-simulation-based research on the effects of interface-induced fluid microstructures on flow resistance
- 2019
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Ingår i: Chinese Journal of Chemical Engineering. - : Elsevier. - 1004-9541 .- 2210-321X. ; 27:6, s. 1403-1415
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Tidskriftsartikel (refereegranskat)abstract
- In modern chemical engineering processes, solid interface involvement is the most important component of process intensification techniques, such as nanoporous membrane separation and heterogeneous catalysis. The fundamental mechanism underlying interfacial transport remains incompletely understood given the complexity of heterogeneous interfacial molecular interactions and the high nonideality of the fluid involved. Thus, understanding the effects of interface-induced fluid microstructures on flow resistance is the first step in further understanding interfacial transport. Molecular simulation has become an indispensable method for the investigation of fluid microstructure and flow resistance. Here, we reviewed the recent research progress of our group and the latest relevant works to elucidate the contribution of interface-induced fluid microstructures to flow resistance. We specifically focused on water, ionic aqueous solutions, and alcohol–water mixtures given the ubiquity of these fluid systems in modern chemical engineering processes. We discussed the effects of the interface-induced hydrogen bond networks of water molecules, the ionic hydration of ionic aqueous solutions, and the spatial distributions of alcohol and alcohol–water mixtures on flow resistance on the basis of the distinctive characteristics of different fluid systems.
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| 9. |
- ZHU, Lu, et al.
(författare)
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Fabrication of MoSi2 coatings on molybdenum and its high-temperature anti-oxidation properties
- 2022
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Ingår i: Transactions of Nonferrous Metals Society of China. - : Elsevier. - 1003-6326 .- 2210-3384. ; 32:3, s. 935-946
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Tidskriftsartikel (refereegranskat)abstract
- Industrial spent MoSi2-based materials were used to fabricate oxidation-resistant coatings on molybdenum via slurry painting in air. The microstructure, phase constituent and high-temperature oxidation behaviors of the coatings at 1500 °C were explored. The results show that the bonding layer is generated in the coatings after sintering, which strengthens the metallurgical combination between the coating and the substrate because of the formation of diffusion layers. Rare cracks appear in the coating using pure MoSi2 (PM coating) while the coating using spent MoSi2 (SM coating) is free of cracks due to decreased thermal expansion mismatch. After oxidation, the oxide scale of PM coating possesses large-sized pores while a relatively dense oxide scale is acquired by SM coating. Compared with PM coating, thinner glassy oxide scale with lower mass gain is obtained by SM coating, exhibiting better anti-oxidation properties at 1500 °C.
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