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Wang X, Zeng Y, Yuan Z, Chen F, Lo WK, Yuan Y, Li T, Yan X, Wang S. Forced capillary wetting of viscoelastic fluids. J Colloid Interface Sci 2024; 662:555-562. [PMID: 38367573 DOI: 10.1016/j.jcis.2024.02.078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 02/05/2024] [Accepted: 02/07/2024] [Indexed: 02/19/2024]
Abstract
HYPOTHESIS Achieving rapid capillary wetting is highly desirable in nature and industries. Previous endeavors have primarily concentrated on passive wetting strategies through surface engineering. However, these approaches are inadequate for high-viscosity fluids due to the significant viscous resistance, especially for non-Newtonian fluids. In contrast, forced wetting emerges as a promising method to address the challenges associated with achieving rapid wetting of non-Newtonian fluids in capillaries. EXPERIMENTS To investigate the forced wetting behavior of viscoelastic fluids in capillaries, we employ Xanthan Gum (XG) aqueous solutions as target fluids with the storage modulus significantly exceeding the loss modulus. We utilize smooth glass capillaries connected to a syringe pump to achieve high moving speeds of up to 1 m/s. FINDINGS Our experiments reveal a significant distinction in the power-law exponent that governs the scaling relationship between the dynamic contact angle and velocity for viscoelastic fluids compared to Newtonian fluids. This exponent is considerably smaller and varies based on the concentration of viscoelastic fluids and the diameter of the capillaries. We suggest that the viscosity dominates the wetting dynamics of viscoelastic fluids, manifested by the contact line morphology-dependent behavior. This insight has significant implications for microfluidics and drug injectability.
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Affiliation(s)
- Xiong Wang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China; Centre for Nature-Inspired Engineering, City University of Hong Kong, Hong Kong, China.
| | - Yijun Zeng
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
| | - Zhenyue Yuan
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
| | - Feipeng Chen
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China
| | - Wai Kin Lo
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China; Centre for Nature-Inspired Engineering, City University of Hong Kong, Hong Kong, China
| | - Yongjiu Yuan
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China; Centre for Nature-Inspired Engineering, City University of Hong Kong, Hong Kong, China
| | - Tong Li
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China; Centre for Nature-Inspired Engineering, City University of Hong Kong, Hong Kong, China
| | - Xiao Yan
- School of Energy and Power Engineering, Chongqing University, Chongqing, China
| | - Steven Wang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China; Centre for Nature-Inspired Engineering, City University of Hong Kong, Hong Kong, China.
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Kim KE, Xue W, Zarzar LD. Liquid-liquid surfactant partitioning drives de wetting of oil from hydrophobic surfaces. J Colloid Interface Sci 2024; 658:179-187. [PMID: 38100974 DOI: 10.1016/j.jcis.2023.12.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Revised: 12/02/2023] [Accepted: 12/08/2023] [Indexed: 12/17/2023]
Abstract
HYPOTHESIS Sessile droplets solubilizing in surfactant solution are frequently encountered in practice, but the factors governing their non-equilibrium dynamics are not well understood. Here, we investigate mechanisms by which solubilizing, sessile oil droplets in aqueous surfactant solution dewet from hydrophobic substrates and spread on hydrophilic substrates. EXPERIMENTS We quantify the dependence of droplet contact line dynamics on drop size and oil, surfactant, and substrate chemistries. We consider halogenated alkane oils as well as aromatic oils and focus on common nonionic nonylphenol ethoxylate surfactants. We correlate these results with measurements of the interfacial tensions. FINDINGS Counter-intuitively, under a range of conditions, we observe complete dewetting of oil from hydrophobic substrates but spreading on hydrophilic substrates. The timescales needed to reach a steady-state contact angle vary widely, with some droplets examined taking over a day. We find that surfactant surface adsorption governs the contact angle on shorter timescales, while partitioning of surfactant from water to oil, and oil solubilization into the water, act on longer timescales to facilitate the complete dewetting. Understanding of the role played by surfactant and oil transport presents opportunities for tailoring sessile droplet behaviors and controlling droplet dynamics under conditions that would previously not have been considered.
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Affiliation(s)
- Kueyoung E Kim
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA.
| | - Wangyang Xue
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA.
| | - Lauren D Zarzar
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA; Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA; Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA.
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3
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Marra D, Orillo E, Toscano G, Petala M, Karapantsios TD, Caserta S. The role of air relative humidity on the wettability of Pseudomonas fluorescens AR11 biofilms. Colloids Surf B Biointerfaces 2024; 237:113831. [PMID: 38508084 DOI: 10.1016/j.colsurfb.2024.113831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 02/22/2024] [Accepted: 02/29/2024] [Indexed: 03/22/2024]
Abstract
Biofilms are complex porous materials formed by microorganisms, polysaccharides, proteins, eDNA, inorganic matter, and water. They are ubiquitous in various environmental niches and are known to grow at solid-liquid, solid-air and air-liquid interfaces, often causing problems in several industrial and sanitary fields. Their removal is a challenge in many applications and numerous studies have been conducted to identify promising chemical species as cleaning agents. While these substances target specific components of biofilm structure, the role of water content in biofilm, and how it can influence wettability and detergent absorption have been quite neglected in the literature. Estimating water content in biofilm is a challenging task due to its heterogeneity in morphology and chemical composition. In this study, we controlled water content in Pseudomonas fluorescens AR 11 biofilms grown on submerged glass slides by regulating environmental relative humidity after drying. Interfacial properties of biofilm were investigated by measuring wetting of water and soybean oil. The morphology of biofilm structure was evaluated using Confocal Laser Scanning Microscopy and Scanning Electron Microscopy. The results showed that biofilm water content has a significant and measurable effect on its wettability, leading to the hypothesis that a preliminary control of water content can play a crucial role in biofilm removal process.
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Affiliation(s)
- Daniele Marra
- DICMaPI, Università di Napoli Federico II, P.le V.Tecchio 80, Napoli 80125, Italy
| | - Emilia Orillo
- DICMaPI, Università di Napoli Federico II, P.le V.Tecchio 80, Napoli 80125, Italy
| | - Giuseppe Toscano
- DICMaPI, Università di Napoli Federico II, P.le V.Tecchio 80, Napoli 80125, Italy
| | - Maria Petala
- Department of Civil Engineering, University Box 487, Thessaloniki 54 124, Greece
| | - Thodoris D Karapantsios
- Department of Chemical Technology and Industrial Chemistry, School of Chemistry, Aristotle University, University Box 116, 541 24 Thessaloniki, Greece
| | - Sergio Caserta
- DICMaPI, Università di Napoli Federico II, P.le V.Tecchio 80, Napoli 80125, Italy; CEINGE, Advanced Biotechnologies, Naples 80145, Italy.
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Nicasy RJK, Waldner C, Erich SJF, Adan OCG, Hirn U, Huinink HP. Liquid uptake in porous cellulose sheets studied with UFI-NMR: Penetration, swelling and air displacement. Carbohydr Polym 2024; 326:121615. [PMID: 38142096 DOI: 10.1016/j.carbpol.2023.121615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 11/15/2023] [Accepted: 11/17/2023] [Indexed: 12/25/2023]
Abstract
Liquid penetration in porous cellulosic materials is crucial in many technological fields. The complex geometry, small pore size, and often fast timescale of liquid uptake makes the process hard to capture. Effects such as swelling, vapor transport, film flow and water transport within cellulosic material makes transport deviate from well-known relations such as Lucas-Washburn and Darcy's Law. In this work it is demonstrated how Ultra-Fast Imaging NMR can be used to simultaneously monitor the liquid distribution and swelling during capillary uptake of water with a temporal- and spatial resolution of 10 ms and 14.5-18 μm respectively. The measurements show that in a cellulose fiber sheet, within the first 65 ms, liquid first penetrates the whole sheet before swelling takes place for another 30 s. Furthermore, it was observed that the liquid front traps 15 v% of air which is slowly replaced by water during the final stage of liquid uptake. Our method makes it possible to simultaneously quantify the concentration of all three phases (solid, liquid and air) within porous materials during processes exceeding 50 ms (5 times the temporal resolution). We hence believe that the proposed method should also be useful to study liquid penetration, or water diffusion, into other porous cellulosic materials like foams, membranes, nonwovens, textiles and films.
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Affiliation(s)
- R J K Nicasy
- Eindhoven University of Technology, Applied Physics Department, P.O. Box 513, Eindhoven, 5600 MB, the Netherlands.
| | - C Waldner
- Institute of Bioproducts and Paper Technology, TU Graz, Inffeldgasse 23, 8010 Graz, Austria; CD Laboratory for Fiber Swelling and Paper Performance, Inffeldgasse 23, 8010 Graz, Austria
| | - S J F Erich
- Eindhoven University of Technology, Applied Physics Department, P.O. Box 513, Eindhoven, 5600 MB, the Netherlands; Organization of Applied Scientific Research, TNO, P.O. Box 49, Delft, 2600 AA, the Netherlands.
| | - O C G Adan
- Eindhoven University of Technology, Applied Physics Department, P.O. Box 513, Eindhoven, 5600 MB, the Netherlands; Organization of Applied Scientific Research, TNO, P.O. Box 49, Delft, 2600 AA, the Netherlands.
| | - U Hirn
- Institute of Bioproducts and Paper Technology, TU Graz, Inffeldgasse 23, 8010 Graz, Austria; CD Laboratory for Fiber Swelling and Paper Performance, Inffeldgasse 23, 8010 Graz, Austria.
| | - H P Huinink
- Eindhoven University of Technology, Applied Physics Department, P.O. Box 513, Eindhoven, 5600 MB, the Netherlands.
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5
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Luo S, Misra RP, Blankschtein D. Water Electric Field Induced Modulation of the Wetting of Hexagonal Boron Nitride: Insights from Multiscale Modeling of Many-Body Polarization. ACS Nano 2024; 18:1629-1646. [PMID: 38169482 DOI: 10.1021/acsnano.3c09811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Understanding the behavior of water contacting two-dimensional materials, such as hexagonal boron nitride (hBN), is important in practical applications, including seawater desalination and energy harvesting. Water, being a polar solvent, can strongly polarize the hBN surface via the electric fields that it generates. However, there is a lack of molecular-level understanding about the role of polarization effects at the hBN/water interface, including its effect on the wetting properties of water. In this study, we develop a theoretical framework that introduces an all-atomistic polarizable force field to accurately model the interactions of water molecules with hBN surfaces. The force field is then utilized to self-consistently describe the water-induced polarization of hBN using the classical Drude oscillator model, including predicting the hBN-water binding energies which are found to be in excellent agreement with diffusion Monte Carlo (DMC) predictions. By carrying out molecular dynamics (MD) simulations, we demonstrate that the polarizable force field yields a water contact angle on multilayered hBN which is in close agreement with the recent experimentally reported values. Conversely, an implicit modeling of the hBN-water polarization energy utilizing a Lennard-Jones (LJ) potential, a commonly utilized approximation in previous MD simulation studies, leads to a considerably lower water contact angle. This difference in the predicted contact angles is attributed to the significant energy-entropy compensation resulting from the incorporation of polarization effects at the hBN-water interface. Our work highlights the importance of self-consistently modeling the hBN-water polarization energy and offers insights into the wetting-related interfacial phenomena of water on polarizable materials.
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Affiliation(s)
- Shuang Luo
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Rahul Prasanna Misra
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Daniel Blankschtein
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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6
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Rosenfeld J, Ganachaud F, Lee D. Nanocomposite colloids prepared by the Ouzo effect. J Colloid Interface Sci 2024; 653:1753-1762. [PMID: 37827013 DOI: 10.1016/j.jcis.2023.09.128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 09/14/2023] [Accepted: 09/21/2023] [Indexed: 10/14/2023]
Abstract
HYPOTHESIS The organization of nanoparticles within nanocomposite colloids can imbue added functionality to these suprastructures. We hypothesize that the arrangement of nanoparticles in nanocomposite colloids can be systematically controlled by inducing co-precipitation of oil and a hydrophilic polymer in the presence of nanoparticles with a range of wetting properties. This process will produce oil core/polymer shell nanocapsules with nanoparticles strategically positioned within the suprastructures. EXPERIMENTS Coprecipitation of oil and polymer in the presence of nanoparticles is performed in glass capillary microfluidics. Silica nanoparticles of varying surface properties and morphology are used to investigate the relationship between nanoparticle wetting properties and nanocolloid morphology. The features of the nanocomposites formed are investigated using electron microscopy, sessile drop, and zeta potential measurements. FINDINGS When spherical nanoparticles with wetting properties ranging from hydrophilic to hydrophobic are used, the nanocomposite morphologies formed range from nanoparticles partially engulfed in the polymer shell to nanoparticles embedded in the oil core of the nanocapsule. The number of nanoparticles introduced in the nanocomposite is adjusted by changing their concentration in the precursor solution. The structure of nanocolloids formed with non-spherical or hollow silica nanoparticles depends on their wetting properties.
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Affiliation(s)
- Joseph Rosenfeld
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 311A Towne Building, 220 South 33rd Street, Philadelphia, PA 19104, United States.
| | - Francois Ganachaud
- Université de Lyon, CNRS, Université Claude Bernard Lyon 1, INSA-Lyon, Université Jean Monnet, UMR5223, Ingénierie des Matériaux Polymères, F69621 Villeurbanne Cedex, France.
| | - Daeyeon Lee
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 311A Towne Building, 220 South 33rd Street, Philadelphia, PA 19104, United States.
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7
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Wang J, Wei Z, Liu Y, Jing X, Liu F, Cao H, Tan Q, Zhao W. Preparation and molecular simulation of an environmentally friendly dust-fixing agent based on chitosan-gelatin. Environ Sci Pollut Res Int 2023; 30:95312-95325. [PMID: 37542689 DOI: 10.1007/s11356-023-28712-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 07/06/2023] [Indexed: 08/07/2023]
Abstract
In order to solve the hazard of coal mine dust, a dust-fixing agent (GC-TG-JFC) was prepared with gelatin, chitosan, octadecanol polyoxyethylene ether, and glutamine transaminase. The experimental conditions and the formulation were optimized by response surface method. The ratio of gelatin, chitosan, octadecanol polyoxyethylene ether, and glutamine transaminase was 0.405:0.211:0.095:0.286 and the dilution ratio was 1:30. The results of product performance test showed that the dust fixation rate could reach 99.95% when the wind speed was 9 m/s. The viscosity of the diluted solution was 42.5 mPa·s. The Forcite module in Materials studio software was used to analyze and calculate the radial distribution concentration, diffusion coefficient, and binding energy of the solution. The results showed that GC-TG-JFC migrated more water molecules to the surface of coal through the action of van der Waals force and hydrogen bond. In addition, the binding energy of water molecules increased and the diffusion coefficient decreased, which improved the binding ability of water molecules with coal. It could be found that GC-TG-JFC had good dust fixation performance by combining experiment and molecular dynamics method.
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Affiliation(s)
- Jinfeng Wang
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China
| | - Zhixin Wei
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China
| | - Yang Liu
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China
| | - Xiaoqing Jing
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China
| | - Fangshun Liu
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China
| | - Huaisheng Cao
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China
| | - Qing Tan
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China
| | - Wenbin Zhao
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China.
- State Key Laboratory of Mining Disaster Prevention and Control Co-found by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, 266590, China.
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8
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Beitollahpoor M, Farzam M, Pesika NS. Friction force-based measurements for simultaneous determination of the wetting properties and stability of superhydrophobic surfaces. J Colloid Interface Sci 2023; 648:161-168. [PMID: 37301141 DOI: 10.1016/j.jcis.2023.05.161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/12/2023] [Accepted: 05/25/2023] [Indexed: 06/12/2023]
Abstract
HYPOTHESIS Contact angle and sliding angle measurements are widely used to characterize superhydrophobic surfaces because of the simplicity and accessibility of the technique. We hypothesize that dynamic friction measurements, with increasing pre-loads, between a water drop and a superhydrophobic surface is more accurate because this technique is less influenced by local surface inhomogeneities and temporal surface changes. EXPERIMENTS A water drop, held by a ring probe which is connected to a dual-axis force sensor, is sheared against a superhydrophobic surface while maintaining a constant preload. From this force-based technique, static and kinetic friction forces measurements are used to characterize the wetting properties of the superhydrophobic surfaces. Furthermore, by applying increased pre-loads to the water drop while shearing, the critical load at which the drop transitions from the Cassie-Baxter to Wenzel state is also measured. FINDINGS The force-based technique predicts sliding angles with reduced standard deviations (between 56 and 64%) compared to conventional optical-based measurements. Kinetic friction force measurements show a higher accuracy (between 35 and 80%) compared to static friction force measurements in characterizing the wetting properties of superhydrophobic surfaces. The critical loads for the Cassie-Baxter to Wenzel state transition allows for stability characterization between seemingly similar superhydrophobic surfaces.
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Affiliation(s)
| | - Melika Farzam
- Chemical and Biomolecular Engineering Department, Tulane University, New Orleans, LA 70118, USA.
| | - Noshir S Pesika
- Chemical and Biomolecular Engineering Department, Tulane University, New Orleans, LA 70118, USA.
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Abstract
MXenes are a class of 2D nanomaterials with exceptional tailor-made properties such as mechano-ceramic nature, rich chemistry, and hydrophilicity, to name a few. However, one of the most challenging issues in any composite/hybrid system is the interfacial wetting. Having a superior integrity of a given composite system is a direct consequence of the proper wettability. While wetting is a fundamental feature, dictating many physical and chemical attributes, most of the common nanomaterials possesses poor affinity due to hydrophobic nature, making them hard to be easily dispersed in a given composite. Thanks to low contact angle, MXenes can offer themselves as an ideal candidate for manufacturing different nano-hybrid structures. Herein this review, it is aimed to particularly study the wettability of MXenes. In terms of the layout of the present study, MXenes are first briefly introduced, and then, the wettability phenomenon is discussed in detail. Upon reviewing the sporadic research efforts conducted to date, a particular attention is paid on the current challenges and research pitfalls to light up the future perspectives. It is strongly believed that taking the advantage of MXene's rich hydrophilic surface may have a revolutionizing role in the fabrication of advanced materials with exceptional features.
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Affiliation(s)
- Massoud Malaki
- Department of Mechanical Engineering, Isfahan University of Technology, Daneshgah e Sanati Hwy, Khomeyni Shahr, Isfahan, 84156-83111, Iran.
| | - Rajender S Varma
- Regional Centre of Advanced Technologies and Materials, Palacký University in Olomouc, Šlechtitelů 27, 783 71, Olomouc, Czech Republic
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Hegner K, Hinduja C, Butt HJ, Vollmer D. Fluorine-Free Super-Liquid-Repellent Surfaces: Pushing the Limits of PDMS. Nano Lett 2023; 23:3116-3121. [PMID: 37039578 PMCID: PMC10141414 DOI: 10.1021/acs.nanolett.2c03779] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 04/06/2023] [Indexed: 06/19/2023]
Abstract
Methods for fabricating super-liquid-repellent surfaces have typically relied on perfluoroalkyl substances. However, growing concerns about the environmental and health effects of perfluorinated compounds have caused increased interest in fluorine-free alternatives. Polydimethylsiloxane (PDMS) is most promising. In contrast to fluorinated surfaces, PDMS-coated surfaces showed only superhydrophobicity. This raises the question whether the poor liquid repellency is caused by PDMS interacting with the probe liquid or whether it results from inappropriate surface morphology. Here, we demonstrate that a well-designed two-tier structure consisting of silicon dioxide nanoparticles combined with surface-tethered PDMS chains allows super-liquid-repellency toward a range of low surface tension liquids. Drops of water-ethanol solutions with surface tensions as low as 31.0 mN m-1 easily roll and bounce off optimized surface structures. Friction force measurements demonstrate excellent surface homogeneity and easy mobility of drops. Our work shows that fluorine-free super-liquid-repellent surfaces can be achieved using scalable fabrication methods and environmentally friendly surface functionalization.
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Carneri M, Ferraro D, Azarpour A, Meggiolaro A, Cremaschini S, Filippi D, Pierno M, Zanchetta G, Mistura G. Sliding and rolling of yield stress fluid droplets on highly slippery lubricated surfaces. J Colloid Interface Sci 2023; 644:487-495. [PMID: 37146485 DOI: 10.1016/j.jcis.2023.04.075] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 04/10/2023] [Accepted: 04/18/2023] [Indexed: 05/07/2023]
Abstract
HYPOTHESIS Droplets of yield stress fluids (YSFs), i.e. fluids that can flow only if they are subjected to a stress above a critical value and otherwise deform like solids, hardly move on solid surfaces due to their high viscosity. The use of highly slippery lubricated surfaces can shed light on the mobility of YSF droplets, which include everyday soft materials, such as toothpaste or mayonnaise, and biological fluids, such as mucus. EXPERIMENTS The spreading and mobility of droplets of aqueous solutions of swollen Carbopol microgels were studied on lubricant infused surfaces. These solutions represent a model system of YSFs. Dynamical phase diagrams were established by varying the concentration of the solutions and the inclination angle of the surfaces. FINDINGS Carbopol droplets deposited on lubricated surfaces could move even at low inclination angles. The droplets were found to slide because of the slip of the flowing oil that covered the solid substrate. However, as the descending speed increased, the droplets rolled down. Rolling was favored at high inclinations and low concentrations. A simple criterion based on the ratio between the yield stress of the Carbopol suspensions and the gravitational stress acting on the Carbopol droplets was found to nicely identify the transition between the two regimes.
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Affiliation(s)
- Mattia Carneri
- Dipartimento di Fisica e Astronomia "G. Galilei", Università di Padova, via Marzolo 8, 35131 Padova, Italy
| | - Davide Ferraro
- Dipartimento di Fisica e Astronomia "G. Galilei", Università di Padova, via Marzolo 8, 35131 Padova, Italy
| | - Afshin Azarpour
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università di Milano, via F.lli Cervi 93, 20054 Segrate, Italy
| | - Alessio Meggiolaro
- Dipartimento di Fisica e Astronomia "G. Galilei", Università di Padova, via Marzolo 8, 35131 Padova, Italy
| | - Sebastian Cremaschini
- Dipartimento di Fisica e Astronomia "G. Galilei", Università di Padova, via Marzolo 8, 35131 Padova, Italy
| | - Daniele Filippi
- Dipartimento di Fisica e Astronomia "G. Galilei", Università di Padova, via Marzolo 8, 35131 Padova, Italy
| | - Matteo Pierno
- Dipartimento di Fisica e Astronomia "G. Galilei", Università di Padova, via Marzolo 8, 35131 Padova, Italy
| | - Giuliano Zanchetta
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università di Milano, via F.lli Cervi 93, 20054 Segrate, Italy.
| | - Giampaolo Mistura
- Dipartimento di Fisica e Astronomia "G. Galilei", Università di Padova, via Marzolo 8, 35131 Padova, Italy.
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12
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Feldmann D, Pinchasik BE. The temperature dependent dynamics and periodicity of dropwise condensation on surfaces with wetting heterogeneities. J Colloid Interface Sci 2023; 644:146-156. [PMID: 37105038 DOI: 10.1016/j.jcis.2023.04.060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 04/07/2023] [Accepted: 04/13/2023] [Indexed: 04/29/2023]
Abstract
HYPOTHESIS Biphilic surfaces, namely surfaces comprising hydrophilic areas with a (super)hydrophobic background, are used in nature and engineering for controlled dropwise condensation and liquid transport. These, however, are highly dependent on the surface temperature and subcooling. EXPERIMENTS Here, biphilic surfaces were cooled inside a rotatable environmental chamber under controlled humidity. The condensation dynamics on the surface was quantified, depending on the subcooling, and compared to uniform superhydrophobic (USH) surfaces. Rates of condensation and transport were analyzed in terms of droplet number and size, covered area and fluid volume over several length scales. Specifically, from microscale condensation to macroscale droplet roll-off. FINDINGS Four phases of condensation were identified: a) initial nucleation, b) droplets on single patches, c) droplets covering adjacent patches and d) multi-patch droplets. Only the latter become mobile and roll off the surface. Cooling the surface to temperatures between T = 2-16 °C shows that lowering the temperature shortens some of the condensation parameters linearly, while others follow a power law, as expected from the theory of condensation. The temperature dependent condensation dynamics on (super)biphilic surfaces is faster in comparison to uniform superhydrophobic surfaces. Nevertheless, within time intervals of a few hours, droplets are mostly immobile. This sets guiding lines for using biphilic surfaces in applications such as water collection, heat transfer and separation processes. Generally, biphilic surfaces are suitable for applications in which fluids should be collected, concentrated and immobilized in specific areas.
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Affiliation(s)
- David Feldmann
- Tel Aviv University School of Mechanical Engineering, Faculty of Engineering, Ramat Aviv 69978, Tel-Aviv, Israel
| | - Bat-El Pinchasik
- Tel Aviv University School of Mechanical Engineering, Faculty of Engineering, Ramat Aviv 69978, Tel-Aviv, Israel.
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Wang X, Yan X, Du J, Ji B, Jalal Inanlu M, Min Q, Miljkovic N. Spreading dynamics of microdroplets on nanostructured surfaces. J Colloid Interface Sci 2023; 635:221-230. [PMID: 36592502 DOI: 10.1016/j.jcis.2022.12.107] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 12/11/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022]
Abstract
HYPOTHESIS Droplet spreading governs various daily phenomena and industrial processes. Insights about microdroplet spreading are limited due to experimental difficulties arising from microdroplet manipulation and substrate wettability control. For droplet sizes approaching the capillary length scale, the gravitational force plays an important role in spreading. In contrast, capillary and viscous forces dominate as the droplet size reduces to smaller length scales. We hypothesize that the dynamic spreading behavior of microdroplets whose radius is far lower than the capillary length differs substantially from established and well understood dynamics. EXPERIMENTS To systematically investigate the spreading dynamics of microdroplets, we develop contact-initiated wetting techniques combined with structuring-independent wettability control to achieve microdroplet (<500 μm) spreading on arbitrary surfaces while eliminating parasitic pinning effects (pining force ∼ 0) and initial impact momentum effects (Weber number ∼ 0). FINDINGS Our experiments reveal that the capillary-driven initial spreading of microdroplets is shorter, with significantly reduced oscillation dampening, when compared to millimeter-scale droplets. Furthermore, spreading along with capillary wave propagation results in coupling between the spreading velocity and dynamic contact angle at the contact line. These findings, along with our proposed microdroplet manipulation platform, may find application in microscale heat transfer, advanced manufacturing, and aerosol transmission studies.
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Affiliation(s)
- Xiong Wang
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA; Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, China
| | - Xiao Yan
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
| | - Jiayu Du
- Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, China
| | - Bingqiang Ji
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Mohammad Jalal Inanlu
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Qi Min
- Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Institute of Nuclear and New Energy Technology, China.
| | - Nenad Miljkovic
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA; Department of Electrical Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan.
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14
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Lee J, Goodwin DJ, Dhenge RM, Nassar J, Bano G, Zeitler JA. Enhanced in-situ liquid transport investigation setup for pharmaceutical tablet disintegration analysis using terahertz radiation. Int J Pharm 2023; 635:122726. [PMID: 36812951 DOI: 10.1016/j.ijpharm.2023.122726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 02/08/2023] [Accepted: 02/11/2023] [Indexed: 02/23/2023]
Abstract
The disintegration process of pharmaceutical solid dosage forms commences on contact with the dissolution medium and continues with subsequent spontaneous imbibition of the medium in the tablet matrix. Identifying the location of the liquid front in situ during imbibition, therefore, plays a significant role in understanding and modelling the disintegration process. Terahertz pulsed imaging (TPI) technology can be used to investigate this process by its ability to penetrate and identify the liquid front in pharmaceutical tablets. However, previous studies were limited to samples suitable for a flow cell environment, i.e. flat cylindrical disk shapes; thus, most commercial tablets could only be measured with prior destructive sample preparation. This study presents a new experimental setup named open immersion to measure a wide range of pharmaceutical tablets in their intact form. Besides, a series of data processing techniques to extract subtle features of the advancing liquid front are designed and utilised, effectively increasing the maximum thickness of tablets that can be analysed. We used the new method and successfully measured the liquid ingress profiles for a set of oval convex tablets prepared from a complex eroding immediate-release formulation.
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Affiliation(s)
- Jongmin Lee
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, CB3 0AS, Cambridge, UK
| | - Daniel J Goodwin
- GSK Ware Research and Development, Park Road, SG12 0DP, Ware, UK
| | - Ranjit M Dhenge
- GSK Ware Research and Development, Park Road, SG12 0DP, Ware, UK
| | - Joelle Nassar
- GSK Ware Research and Development, Park Road, SG12 0DP, Ware, UK
| | - Gabriele Bano
- GSK Ware Research and Development, Park Road, SG12 0DP, Ware, UK
| | - J Axel Zeitler
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, CB3 0AS, Cambridge, UK.
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15
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Fudge BD, Cimpeanu R, Antkowiak A, Castrejón-Pita JR, Castrejón-Pita AA. Drop splashing after impact onto immiscible pools of different viscosities. J Colloid Interface Sci 2023; 641:585-594. [PMID: 36963252 DOI: 10.1016/j.jcis.2023.03.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 02/14/2023] [Accepted: 03/05/2023] [Indexed: 03/19/2023]
Abstract
Droplet impact onto liquid pools is a canonical scenario relevant to numerous natural phenomena and industrial processes. However, despite their ubiquity, multi-fluid systems with the drop and pool consisting of different liquids are far less well understood. Our hypothesis is that the post-impact dynamics greatly depends on the pool-to-droplet viscosity ratioμp/μd, which we explore over a range of six orders of magnitude using a combination of experiments and theoretical approaches (mathematical modelling and direct numerical simulation). Our findings indicate that in this scenario the splashing threshold and the composition of the ejecta sheet are controlled by the viscosity ratio. We uncover that increasing the pool viscosity decreases the splashing threshold for high viscosity pools (μp/μd≳35) when the splash comes from the droplet. By contrast, for low viscosity pools, the splash sheet comes from the pool and increasing the pool viscosity increases the splashing threshold. Surprisingly, there are conditions for which no splashing is observed under the conditions attainable in our laboratory. Furthermore, considering the interface velocity together with asymptotic arguments underlying the generation of the ejecta has allowed us to understand meaningful variations in the pressure during impact and rationalise the observed changes in the splashing threshold.
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Affiliation(s)
- Ben D Fudge
- Department of Engineering Science, University of Oxford, Oxford OX1 3PJ, United Kingdom.
| | - Radu Cimpeanu
- Mathematics Institute, University of Warwick, Coventry CV4 7AL, United Kingdom; Mathematical Institute, University of Oxford, Oxford OX2 6GG, United Kingdom; Department of Mathematics, Imperial College London, London SW7 2AZ, United Kingdom.
| | - Arnaud Antkowiak
- Institut Jean le Rond ∂'Alembert, Sorbonne Université, CNRS, F-75005 Paris, France.
| | - J Rafael Castrejón-Pita
- Department of Mechanical Engineering, University College London, London WC1E 7JE, United Kingdom.
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16
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Dong R, Nassar M, Friend B, Teckoe J, Zeitler JA. Studying the dissolution of immediate release film coating using terahertz pulsed imaging. Int J Pharm 2022; 630:122456. [PMID: 36503850 DOI: 10.1016/j.ijpharm.2022.122456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 11/27/2022]
Abstract
Coated tablets introduce complexity to the dissolution process, even with readily soluble immediate release coating layers. Therefore, a more detailed understanding of the physical steps involved in the dissolution process can improve the efficiency of formulation and process design. The current study uses terahertz pulsed imaging to visualise the hydration process of microcrystalline cellulose (MCC) tablet cores that were film coated with an immediate release coating formulation upon exposure to the dissolution medium. Film coated tablets that were prepared from three levels of core porosity (10%, 20% and 30%) and with coating thickness in the range of 30μm to 250μm were investigated. It was possible to resolve and quantify the distinct stages of wetting of the coating layer, swelling of the MCC particles at the core surface, and dissolution of the coating layer followed by the ingress of dissolution media into the tablet core. The liquid transport process through the coating layer was highly consistent and scalable. The penetration rate through the coating layer and the tablet core both strongly depended on coating thickness and core porosity.
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17
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Long J, Li Y, Ouyang Z, Xi M, Wu J, Lin J, Xie X. A universal approach to recover the original superhydrophilicity of micro/nano-textured metal or metal oxide surfaces. J Colloid Interface Sci 2022; 628:534-44. [PMID: 36007418 DOI: 10.1016/j.jcis.2022.08.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 07/20/2022] [Accepted: 08/07/2022] [Indexed: 11/20/2022]
Abstract
Micro/nano-textured metal or metal oxide surfaces that are naturally superhydrophilic will spontaneously transform into hydrophobic even superhydrophobic after being exposed to ambient air due to the adsorption of airborne organics. This fast wettability transition not only affects the true evaluation of surface wettability but also deteriorates the application performance. Albeit the mechanisms responsible for the wettability transition have been clarified, there is no universal method to recover the initial superhydrophilicity, and how the surface morphology affects the wettability transition is still unclear. Herein, we observe and compare the wettability transition of a wide variety of micro/nano-textured metal or metal oxide surfaces and propose a solvent cleaning method to recover their original superhydrophilicity. We prove that the spontaneously adsorbed organics can be removed by our proposed cleaning method while maintaining the original surface morphology and composition. Our proposed cleaning method is valid for both micro/nano-textured metal and metal oxide surfaces. We also prove that the rate of the wettability transition is not primarily affected by the specific area of surface structures but by the closeness of structural arrangement. Densely packed surface nanostructures can significantly delay the wettability transition by suppressing the diffusion of organic molecules. Our results help the true evaluation of surface wettability and provide a route for the design and preparation of long-lasting superhydrophilic surfaces.
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18
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Li W, Liang Y, Li B, Feng J. Sonoprocessing of wetting of SiC by liquid Al: A thermodynamic and kinetic study. Ultrason Sonochem 2022; 88:106092. [PMID: 35878510 PMCID: PMC9310135 DOI: 10.1016/j.ultsonch.2022.106092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 07/01/2022] [Accepted: 07/05/2022] [Indexed: 06/15/2023]
Abstract
The sonoprocessing of droplet spreading during the wetting process of molten aluminum droplets on SiC ceramic substrates at 700 °C is investigated in this paper. When wetting is assisted by a 20 kHz frequency ultrasonic field, the wettability of liquid metal gets enhanced, which has been determined by the variations in thermodynamic energy and wetting kinetics. Wetting kinetic characteristics are divided into two stages according to pinning and depinning states of substrate/droplet contact lines. The droplet is static when the contact line is pinning, while it is forced to move when the contact line is depinning. When analyzing the pinning stage, high-speed photography reveals the evidence of oxide films being rapidly crushed outside the aluminum droplet. In this work, atomic models of spherical Al core being wrapped by alumina shell are tentatively built, whose dioxide microstructures are being transformed from face-centered cubic into liquid at the atomic scale. At the same time, the wetting experiment reveals that the oxide films show changes in the period of sonoprocessing from 3rd to 5th second. During the ultrasonic spreading behavior in the late stage, there is a trend of evident expansion of the base contact area. The entire ultrasonic process lasts for no longer than 10 s. With the aid of ultrasonic sinusoidal waves, the wettability of metal Al gets a rapid improvement. Both molecular dynamic (MD) investigations and the experiments results reveal that the precursor film phenomenon is never found unless wetting is assisted by ultrasonic treatments. However, the precursor film appears near the triple line after using ultrasonics in the droplet wetting process, whose formation is driven by ultrasonic oscillations. Due to the precursor film, the ultrasonic wetting contact angle is lower than the non-ultrasonic contact angle. In addition, the time-variant effective ultrasonic energy has been quantitatively evaluated. The numerical expressions of thermodynamic variables are well verified by former ultrasonic spreading test results, which altogether provide an intrinsic explanation of the fast-decreasing contact angle of Al/SiC.
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Affiliation(s)
- Wendi Li
- School of Materials Science and Engineering, State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, 150001, China.
| | - Yuxin Liang
- School of Materials Science and Engineering, Harbin Institute of Technology, 150001, China.
| | - Bangsheng Li
- School of Materials Science and Engineering, State Key Laboratory of Advanced Welding and Joining, National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, 150001, China
| | - Jicai Feng
- School of Materials Science and Engineering, State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, 150001, China.
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19
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Cai J, Chen Y, Liu Y, Li S, Sun C. Capillary imbibition and flow of wetting liquid in irregular capillaries: A 100-year review. Adv Colloid Interface Sci 2022; 304:102654. [PMID: 35468356 DOI: 10.1016/j.cis.2022.102654] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 03/17/2022] [Accepted: 03/20/2022] [Indexed: 01/29/2023]
Abstract
Capillary imbibition, such as plant roots taking up water, reservoir rocks absorbing brine and a tissue paper wiping stains, is pervasive occurred in nature, engineering and industrial fields, as well as in our daily life. This phenomenon is earliest modeled through the process that wetting liquid is spontaneously propelled by capillary pressure into regular geometry models. Recent studies have attracted more attention on capillary-driven flow models within more complex geometries of the channel, since a detailed understanding of capillary imbibition dynamics within irregular geometry models necessitates the fundamentals to fluid transport mechanisms in porous media with complex pore topologies. Herein, the fundamentals and concepts of different capillary imbibition models in terms of geometries over the past 100 years are reviewed critically, such as circular and non-circular capillaries, open and closed capillaries with triangular/rectangular cross-sections, and heterogeneous geometries with axial variations. The applications of these models with appropriate conditions are discussed in depth accordingly, with a particular emphasize on the capillary flow pattern as a consequence of capillary geometry. In addition, a universal model is proposed based on the dynamic wetting condition and equivalent cylindrical geometry to describe the capillary imbibition process in terms of various solid topologies. Finally, future research is suggested to focus on analyzing the dynamics during corner flow, the snap-off of wetting fluid, the capillary rise of non-Newtonian fluids and applying accurate physical simulation methods on capillary-driven flow processes. Generally, this review provides a comprehensive understanding of the capillary-driven flow models inside various capillary geometries and affords an overview of potential advanced developments to enhance the current understanding of fluid transport mechanisms in porous media.
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20
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Mérai L, Deák Á, Dékány I, Janovák L. Fundamentals and utilization of solid/ liquid phase boundary interactions on functional surfaces. Adv Colloid Interface Sci 2022; 303:102657. [PMID: 35364433 DOI: 10.1016/j.cis.2022.102657] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 03/23/2022] [Accepted: 03/24/2022] [Indexed: 12/16/2022]
Abstract
The affinity of macroscopic solid surfaces or dispersed nano- and bioparticles towards liquids plays a key role in many areas from fluid transport to interactions of the cells with phase boundaries. Forces between solid interfaces in water become especially important when the surface texture or particles are in the colloidal size range. Although, solid-liquid interactions are still prioritized subjects of materials science and therefore are extensively studied, the related literature still lacks in conclusive approaches, which involve as much information on fundamental aspects as on recent experimental findings related to influencing the wetting and other wetting-related properties and applications of different surfaces. The aim of this review is to fill this gap by shedding light on the mechanism-of-action and design principles of different, state-of-the-art functional macroscopic surfaces, ranging from self-cleaning, photoreactive or antimicrobial coatings to emulsion separation membranes, as these surfaces are gaining distinguished attention during the ongoing global environmental and epidemic crises. As there are increasing numbers of examples for stimulus-responsive surfaces and their interactions with liquids in the literature, as well, this overview also covers different external stimulus-responsive systems, regarding their mechanistic principles and application possibilities.
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21
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Al Balushi KM, Sefiane K, Orejon D. Binary mixture droplet wetting on micro-structure decorated surfaces. J Colloid Interface Sci 2022; 612:792-805. [PMID: 35065463 DOI: 10.1016/j.jcis.2021.12.171] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/17/2021] [Accepted: 12/26/2021] [Indexed: 10/19/2022]
Abstract
Liquid surface tension as well as solid structure play a paramount role on the intimate wetting and non-wetting regimes and interactions between liquids droplets and solid substrates. We hypothesise that the coupling of these two variables, independently addressed in the past, eventually offer a wider range of understanding to the surface science and interfacial communities. In this work, intrinsically hydrophobic micro-pillared surfaces varying in the spacing between structures, and pure ethanol, pure water and their binary mixtures (as well as acetone-water and ethylene glycol-water mixtures) are utilised, accessing a wide range of substrate solid fractions and liquid surface tensions experimentally. Wettability measurements are carried out at different azimuthal directions to exemplify the wetting/non-wetting behaviour as well as the droplet asymmetry function of both liquid composition and structure spacing. Our findings reveal that high water concentration droplets, i.e., high surface tension fluids, sit in the Cassie-Baxter regime while partial non-wetting Wenzel or mixed-mode regimes with enhanced droplet asymmetry ensuing for medium and high ethanol concentrations, i.e., low surface tension fluids, below certain micropillar spacing. Beyond micropillar spacing s ≥ 40 µm, the impact of the surface structure on the droplet shape is negligible, and droplets adopt a similar contact angle and circular shape as on a flat smooth hydrophobic surface. Wetting and non-wetting regimes are then supported by classical wetting theories and equations. A wetting regime map for a wide range of surface tension fluids and/or their mixtures on a wide domain of solid fractions is then proposed.
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Affiliation(s)
- Khaloud Moosa Al Balushi
- Institute for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FD, Scotland, UK; Department of Engineering, The University of Technology and Applied Sciences, Suhar 311, Oman
| | - Khellil Sefiane
- Institute for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FD, Scotland, UK
| | - Daniel Orejon
- Institute for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FD, Scotland, UK; International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
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22
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Piovano P, Velčić I. Microscopical Justification of Solid-State Wetting and Dewetting. J Nonlinear Sci 2022; 32:32. [PMID: 35400851 PMCID: PMC8976832 DOI: 10.1007/s00332-022-09783-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 02/23/2022] [Indexed: 06/14/2023]
Abstract
The continuum model related to the Winterbottom problem, i.e., the problem of determining the equilibrium shape of crystalline drops resting on a substrate, is derived in dimension two by means of a rigorous discrete-to-continuum passage by Γ -convergence of atomistic models taking into consideration the atomic interactions of the drop particles both among themselves and with the fixed substrate atoms. As a byproduct of the analysis, effective expressions for the drop surface anisotropy and the drop/substrate adhesion parameter appearing in the continuum model are characterized in terms of the atomistic potentials, which are chosen of Heitmann-Radin sticky-disk type. Furthermore, a threshold condition only depending on such potentials is determined distinguishing the wetting regime, where discrete minimizers are explicitly characterized as configurations contained in an infinitesimally thick layer, i.e., the wetting layer, on the substrate, from the dewetting regime. In the latter regime, also in view of a proven conservation of mass in the limit as the number of atoms tends to infinity, proper scalings of the minimizers of the atomistic models converge (up to extracting a subsequence and performing translations on the substrate surface) to a bounded minimizer of the Winterbottom continuum model satisfying the volume constraint.
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Affiliation(s)
- Paolo Piovano
- Politecnico di Milano, Dipartimento di Matematica, P.zza Leonardo da Vinci 32, 20133 Milan, Italy
- WPI c/o Research Platform MMM “Mathematics-Magnetism-Materials”, Fak. Mathematik, Univ. Wien, 1090 Vienna, Austria
| | - Igor Velčić
- Faculty of Electrical Engineering and Computing, University of Zagreb, Unska 3, 10000 Zagreb, Croatia
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Böddeker TJ, Rosowski KA, Berchtold D, Emmanouilidis L, Han Y, Allain FHT, Style RW, Pelkmans L, Dufresne ER. Erratum: Publisher Correction: Non-specific adhesive forces between filaments and membraneless organelles. Nat Phys 2022; 18:601. [PMID: 35583413 PMCID: PMC9106589 DOI: 10.1038/s41567-022-01600-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
[This corrects the article DOI: 10.1038/s41567-022-01537-8.].
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Affiliation(s)
| | | | - Doris Berchtold
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | | | - Yaning Han
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | | | | | - Lucas Pelkmans
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
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Dong R, Zeitler JA. Visualising liquid transport through coated pharmaceutical tablets using Terahertz pulsed imaging. Int J Pharm 2022; 619:121703. [PMID: 35351529 DOI: 10.1016/j.ijpharm.2022.121703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 03/15/2022] [Accepted: 03/22/2022] [Indexed: 11/23/2022]
Abstract
Dissolution of pharmaceutical tablets is a complex process, especially for coated tablets where layered structures form an additional barrier for liquid transport into the porous tablet matrix. A better understanding of the role of the coating structure in the mass transport processes that govern drug release, starting with the wetting of the coating layer by the dissolution medium, can benefit the formulation design and optimisation of the production. For this study, terahertz pulsed imaging was used to investigate how dissolution medium can penetrate coated tablets. In order to focus on the fundamental process, the model system for this proof-of-principle study consisted of tablet cores made from pure microcrystalline cellulose compacted to a defined porosity coated with Opadry II, a PVA-based immediate release coating blend. The coating was applied to a single side of flat-faced tablets using vacuum compression moulding. It was possible to resolve the hydration of the coating layer and the subsequent liquid ingress into the dry tablet core. The analysis revealed a discontinuity in density at the interface between coating and core, where coating polymer could enter the pore space at the immediate surface of the tablet cores during the coating process. This structure affected the liquid transport of the dissolution medium into the core. We found evidence for the formation of a gel layer upon hydration of the coating polymer. The porosity of the tablet core impacted the quality of coating and thus affected its dissolution performance (r = 0.6932 for the effective liquid penetration rate RPeff and the core porosity). This study established a methodology and can facilitate a more in-depth understanding of the role of coating on tablet dissolution.
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25
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Pei J, Liao Y, Li Q, Shi K, Fu J, Hu X, Huang Z, Xue L, Xiao X, Liu K. Single-layer graphene prevents Cassie- wetting failure of structured hydrophobic surface for efficient condensation. J Colloid Interface Sci 2022; 615:302-308. [PMID: 35149348 DOI: 10.1016/j.jcis.2022.01.157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/22/2022] [Accepted: 01/24/2022] [Indexed: 11/18/2022]
Abstract
HYPOTHESIS Structured hydrophobic surfaces often suffer from Cassie-wetting failure due to trapped water in structure gaps for a long-term operation. Sustainable Cassie-wetting on such surface could be achieved by coating an atom-thick and moisture-impermeable graphene on it. EXPERIMENTS Water contact angles were measured to clarify the effect of graphene on wetting, and water impermeability was verified by moisture deposition and evaporation. Sliding angle measurements and vapor condensation were carried out to demonstrate the stable Cassie-state wetting and application. FINDINGS Interestingly we found the graphene does not significantly disrupt the wetting behavior of the structured hydrophobic surface, showing a wettability transparency. Moreover, the impermeability of graphene keeps moisture away from the structure gaps. Owning to the combination of these two properties, droplets on the graphene-coated structured surface exhibit a stable Cassie-state hydrophobic wetting, even under the situation of moisture deposition and evaporation. Using the modified surface, we also found a 40-100% increase in condensation efficiency for a 5-hour vapor condensation at a subcooling of 40 °C. These results suggest an effective strategy to prevent Cassie-wetting failure of structured hydrophobic surface and are expected to promote its further application in more complex conditions.
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Affiliation(s)
- Junxian Pei
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan, Hubei 430072, China; State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource & Hydropower, Sichuan University, Chengdu 610065, China
| | - Yutian Liao
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan, Hubei 430072, China
| | - Qian Li
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan, Hubei 430072, China
| | - Kui Shi
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan, Hubei 430072, China
| | - Jia Fu
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan, Hubei 430072, China
| | - Xuejiao Hu
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan, Hubei 430072, China
| | - Zhi Huang
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan, Hubei 430072, China.
| | - Longjian Xue
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan, Hubei 430072, China.
| | - Xu Xiao
- Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou, Zhejiang 313001, China; School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Kang Liu
- MOE Key Laboratory of Hydraulic Machinery Transients, School of Power and Mechanical Engineering, Wuhan University, Wuhan, Hubei 430072, China.
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Li Z, Xu Z, He P, Ma Z, Chen S, Yan J. Dependence of wetting on cavitation during the spreading of a filler droplet on the ultrasonically agitated Al substrate. Ultrason Sonochem 2022; 82:105893. [PMID: 34969000 PMCID: PMC8799618 DOI: 10.1016/j.ultsonch.2021.105893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/22/2021] [Accepted: 12/23/2021] [Indexed: 06/14/2023]
Abstract
The cavitation characteristics during the spreading of a pure Sn liquid droplet subjected to ultrasonication were studied for the first time through high-speed photography to reveal the wetting mechanism. Ultrasonic vibration realized the spreading of Sn droplet on the nonwetting pure Al substrate. However, the oxide layer of the substrate at the spreading front is difficult to remove. The high-speed photography result shows that a noncavitation region consistently appears at the spreading front, because the acoustic pressure is below the cavitation threshold of 1.26 MPa. In particular, the width of the noncavitation region gradually increases as the size of the spreading area increases. Such a result accounts for the condition wherein the oxide layer at the spreading front is difficult to remove. Furthermore, the bubble density during spreading gradually decreases due to the decreased acoustic pressure of the thinned liquid. Finally, the bubble dynamics were calculated to verify the wetting mechanism.
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Affiliation(s)
- Zhengwei Li
- State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China
| | - Zhiwu Xu
- State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China.
| | - Peng He
- State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China.
| | - Zhongwei Ma
- State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China
| | - Shu Chen
- State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China
| | - Jiuchun Yan
- State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China
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Böddeker TJ, Rosowski KA, Berchtold D, Emmanouilidis L, Han Y, Allain FHT, Style RW, Pelkmans L, Dufresne ER. Non-specific adhesive forces between filaments and membraneless organelles. Nat Phys 2022; 18:571-578. [PMID: 35582428 PMCID: PMC9106579 DOI: 10.1038/s41567-022-01537-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 02/04/2022] [Indexed: 05/07/2023]
Abstract
Many membraneless organelles are liquid-like domains that form inside the active, viscoelastic environment of living cells through phase separation. To investigate the potential coupling of phase separation with the cytoskeleton, we quantify the structural correlations of membraneless organelles (stress granules) and cytoskeletal filaments (microtubules) in a human-derived epithelial cell line. We find that microtubule networks are substantially denser in the vicinity of stress granules. When microtubules are depolymerized, the sub-units localize near the surface of the stress granules. We interpret these data using a thermodynamic model of partitioning of particles to the surface and bulk of the droplets. In this framework, our data are consistent with a weak (≲k B T) affinity of the microtubule sub-units for stress granule interfaces. As microtubules polymerize, their interfacial affinity increases, providing sufficient adhesion to deform droplets and/or the network. Our work suggests that proteins and other objects in the cell have a non-specific affinity for droplet interfaces that increases with the contact area and becomes most apparent when they have no preference for the interior of a droplet over the rest of the cytoplasm. We validate this basic physical phenomenon in vitro through the interaction of a simple protein-RNA condensate with microtubules.
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Affiliation(s)
| | | | - Doris Berchtold
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | | | - Yaning Han
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | | | | | - Lucas Pelkmans
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
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28
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Ding W, Dorao CA, Fernandino M. Improving superamphiphobicity by mimicking tree-branch topography. J Colloid Interface Sci 2021; 611:118-128. [PMID: 34933190 DOI: 10.1016/j.jcis.2021.12.056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 12/07/2021] [Accepted: 12/08/2021] [Indexed: 11/17/2022]
Abstract
when a droplet impacts on a superhydrophobic structured surface below a certain impact velocity, the droplet can bounce off completely from the surface. However, above such velocity a fraction of the droplet will pin on the surface. Surfaces capable of repelling water droplets are ubiquitous in nature or have been artificially fabricated. However, as the surface tension of the liquid is reduced, the capability of the surface to remain non-wetting gets hindered. Despite progress in previous research, the understanding and development of superamphiphobic surface to impacting low surface tension droplets remains elusive. It is proposed that multi-layer re-entrant like roughness can further enhance the anti-wetting properties also for low surface tension fluids. In this work, we produce patterned conical micro-structures with lateral nano-sized roughness. Furthermore, the droplet impact experiments are conducted on various surfaces with variable surface tensions (27 mN/m - 72 mN/m) by using droplets with different Weber numbers (2-170). We show that conical microstructures with lateral roughness mimicking tree-branches provides a surface topology capable of absorbing the force exerted by the droplet during the impact which prevents the droplet from pinning on the surface at higher impact velocity even for low surface tension droplets. Our study has significance for understanding the liquid interaction mechanism with the surface during the impact process and for the associated surface design considerations.
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Affiliation(s)
- Wenwu Ding
- Department of Energy and Process Engineering. Norwegian University of Science and Technology, Trondheim 7491, Norway
| | - Carlos Alberto Dorao
- Department of Energy and Process Engineering. Norwegian University of Science and Technology, Trondheim 7491, Norway
| | - Maria Fernandino
- Department of Energy and Process Engineering. Norwegian University of Science and Technology, Trondheim 7491, Norway.
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29
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Angelopoulou D, Meunier V, Forny L, Niederreiter G, Palzer S, Salman AD. Influence of localized thermal effects on the reconstitution kinetics of lactose-coated whole milk powder. Food Res Int 2021; 150:110774. [PMID: 34865789 DOI: 10.1016/j.foodres.2021.110774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 10/04/2021] [Accepted: 10/18/2021] [Indexed: 11/16/2022]
Abstract
Reconstitution of dairy powders is strongly influenced by the presence and physical state of fat on the particle surface. The present study investigates the effect of a micronized lactose coating on the physical state of the fat and the reconstitution kinetics of whole milk powder at four different temperatures (4/21/40/60 °C) and two stirring rates (400/800 rpm). For this purpose, two types of micronized lactose were used as coating materials: crystalline and amorphous. At 4 °C and 21 °C, the coated powders sink and are reconstituted faster than pure whole milk powder, regardless of the stirring rate applied. At 40/60 °C and 400 rpm, although the amorphous micronized lactose coating leads to a significant decrease in the reconstitution time, the crystalline coating has the opposite effect (or no effect). This discrepancy is related to the large differences in terms of dissolution enthalpy between the two micronized lactose physical states. It is posited that the dissolution of the coating material causes a temperature shift at the powder-water interface which could hamper the complete melting of surface fat and influence its viscosity, thereby affecting wetting and sinking. These differences are overcome at a high stirring rate (800 rpm) or if agglomerated whole milk powder is used as the host material.
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Affiliation(s)
- Diamanto Angelopoulou
- Department of Chemical and Biological Engineering, University of Sheffield, S1 3JD Sheffield, UK
| | - Vincent Meunier
- Nestlé Research, Vers-chez-les-blanc, 1000 Lausanne 26, Switzerland
| | - Laurent Forny
- Nestlé Product Technology Center, Route de Chavornay 3, 1350 Orbe, Switzerland
| | | | - Stefan Palzer
- Nestlé SA, Avenue Nestlé 55, 1800 Vevey, Switzerland
| | - Agba D Salman
- Department of Chemical and Biological Engineering, University of Sheffield, S1 3JD Sheffield, UK.
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30
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Lößlein SM, Mücklich F, Grützmacher PG. Topography versus chemistry - How can we control surface wetting? J Colloid Interface Sci 2021; 609:645-656. [PMID: 34839911 DOI: 10.1016/j.jcis.2021.11.071] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 11/12/2021] [Accepted: 11/13/2021] [Indexed: 02/02/2023]
Abstract
HYPOTHESIS Wetting characterization and the production of engineered surfaces showing distinct contact angles or spreading behavior is of major importance for many industrial and scientific applications. As chemical composition plays a major role in the wetting behavior of flat samples, wettability, capillary forces and resulting droplet spreading on anisotropic surface patterns are expected to be highly dependent on surface chemistry as well. EXPERIMENTS To gain understanding of the fundamental principles of the interplay between surface topography and surface chemistry regarding water wettability, anisotropic line patterns were produced on steel samples in a direct laser writing process. Homogeneous surface coatings allowed for a chemical masking of the laser patterns and therewith the identification of the influence of surface chemistry on static contact angles and wetting anisotropy. FINDINGS While a carbon coating leads to pronounced wettability and spreading along the topographic anisotropy, an inert gold-palladium coating can fully suppress anisotropic droplet spreading. Model calculations show that an amorphous carbon coating leads to Wenzel wetting while the gold-palladium coating causes air inclusions between the water and the surface in the Cassie-Baxter wetting state. Only in combination with the right chemical composition of the surface, directional patterns show their potential of anisotropic wetting behavior.
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Affiliation(s)
- Sarah Marie Lößlein
- Chair of Functional Materials, Department of Material Science and Engineering, Campus D3 3, 66123 Saarbrücken, Germany.
| | - Frank Mücklich
- Chair of Functional Materials, Department of Material Science and Engineering, Campus D3 3, 66123 Saarbrücken, Germany.
| | - Philipp G Grützmacher
- Chair of Functional Materials, Department of Material Science and Engineering, Campus D3 3, 66123 Saarbrücken, Germany.
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31
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Baales J, Zeisler-Diehl VV, Malkowsky Y, Schreiber L. Interaction of surfactants with barley leaf surfaces: time-dependent recovery of contact angles is due to foliar uptake of surfactants. Planta 2021; 255:1. [PMID: 34837118 PMCID: PMC8626361 DOI: 10.1007/s00425-021-03785-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 11/10/2021] [Indexed: 06/13/2023]
Abstract
Time-dependent contact angle measurements of pure water on barley leaf surfaces allow quantifying the kinetics of surfactant diffusion into the leaf. Barley leaf surfaces were sprayed with three different aqueous concentrations (0.1, 1.0 and 10%) of a monodisperse (tetraethylene glycol monododecyl ether) and a polydisperse alcohol ethoxylate (BrijL4). After 10 min, the surfactant solutions on the leaf surfaces were dry leading to surfactant coverages of 1, 10 and 63 µg cm-2, respectively. The highest surfactant coverage (63 µg cm-2) affected leaf physiology (photosynthesis and water loss) rapidly and irreversibly and leaves were dying within 2-6 h. These effects on leaf physiology did not occur with the lower surfactant coverages (1 and 10 µg cm-2). Directly after spraying of 0.1 and 1.0% surfactant solution and complete drying (10 min), leaf surfaces were fully wettable for pure water and contact angles were 0°. Within 60 min (0.1% surfactant) and 6 h (1.0% surfactant), leaf surfaces were non-wettable again and contact angles of pure water were identical to control leaves. Scanning electron microscopy investigations directly performed after surfactant spraying and drying indicated that leaf surface wax crystallites were partially or fully covered by surfactants. Wax platelets with unaltered microstructure were fully visible again within 2 to 6 h after treatment with 0.1% surfactant solutions. Gas chromatographic analysis showed that surfactant amounts on leaf surfaces continuously disappeared over time. Our results indicate that surfactants, applied at realistic coverages between 1 and 10 µg cm-2 to barley leaf surfaces, leading to total wetting (contact angles of 0°) of leaf surfaces, are rapidly taken up by the leaves. As a consequence, leaf surface non-wettability is fully reappearing. An irreversible damage of the leaf surface fine structure leading to enhanced wetting and increased foliar transpiration seems highly unlikely at low surfactant coverages of 1 µg cm-2.
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Affiliation(s)
- Johanna Baales
- Institute of Cellular and Molecular Botany, Department of Ecophysiology, University of Bonn, Kirschallee 1, 53115, Bonn, Germany
| | - Viktoria V Zeisler-Diehl
- Institute of Cellular and Molecular Botany, Department of Ecophysiology, University of Bonn, Kirschallee 1, 53115, Bonn, Germany
| | - Yaron Malkowsky
- Nees Institute for Biodiversity of Plants, University of Bonn, Meckenheimer Allee 170, 53115, Bonn, Germany
| | - Lukas Schreiber
- Institute of Cellular and Molecular Botany, Department of Ecophysiology, University of Bonn, Kirschallee 1, 53115, Bonn, Germany.
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32
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Xu W, Lambæk A, Holm SS, Furbo-Halken A, Elberling B, Ambus PL. Effects of experimental fire in combination with climate warming on greenhouse gas fluxes in Arctic tundra soils. Sci Total Environ 2021; 795:148847. [PMID: 34246149 DOI: 10.1016/j.scitotenv.2021.148847] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 06/30/2021] [Accepted: 06/30/2021] [Indexed: 06/13/2023]
Abstract
The frequency and severity of fire is increasing in Arctic tundra regions with climate change. Here we investigated effects of experimental low-intensity fire and shrub cutting, in combination with warming, on soil biogeochemical cycles and post-fire greenhouse gas (GHG) emissions in a dry heath tundra, West Greenland. We performed in vitro incubation experiments based on soil samples collected for up to two years after the fire. We observed tendency for increased soil nitrate (14-fold) and significant increases in soil ammonium and phosphate (four-fold and five-fold, respectively) two years after the fire, but no effects of shrub cutting on these compounds. Thus, changes appear to be largely due to fire effects rather than indirect effects by vegetation destruction. Two years after fire, nitrous oxide (N2O) and carbon dioxide (CO2) production was significantly increased (three-fold and 32% higher, respectively), in burned than unburned soils, while methane (CH4) uptake remained unchanged. This stimulated N2O and CO2 production by the fire, however, was only apparent under conditions when soil was at maximum water holding capacity, suggesting that fire effects can be masked under dry conditions in this tundra ecosystem. There were positive effects by modest 2.5 °C warming on CO2 production in control but not in burned soils, suggesting that fire may decrease the temperature response in soil respiration. Methane uptake was neither altered by the modest warming in shrub-cut nor in burned soils after two years, suggesting that the removal of vegetation may play a key role in controlling future temperature response of CH4 oxidation. Altogether, our results show that post-fire tundra soils have the potential to enhance soil GHG emissions (e.g. N2O and CO2) especially during episodes with wet soil conditions. On the other hand, the lack of warming responses in post-fire soil respiration may weaken this positive feedback to climate change.
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Affiliation(s)
- Wenyi Xu
- Center for Permafrost, Department of Geosciences and Natural Resource Management, University of Copenhagen, 1350 Copenhagen K, Denmark.
| | - Anders Lambæk
- Center for Permafrost, Department of Geosciences and Natural Resource Management, University of Copenhagen, 1350 Copenhagen K, Denmark
| | - Signe Skjold Holm
- Center for Permafrost, Department of Geosciences and Natural Resource Management, University of Copenhagen, 1350 Copenhagen K, Denmark
| | - Annesofie Furbo-Halken
- Center for Permafrost, Department of Geosciences and Natural Resource Management, University of Copenhagen, 1350 Copenhagen K, Denmark
| | - Bo Elberling
- Center for Permafrost, Department of Geosciences and Natural Resource Management, University of Copenhagen, 1350 Copenhagen K, Denmark
| | - Per Lennart Ambus
- Center for Permafrost, Department of Geosciences and Natural Resource Management, University of Copenhagen, 1350 Copenhagen K, Denmark
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33
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Song JW, Fan LW. Understanding the effects of pressure on the contact angle of water on a silicon surface in nitrogen gas environment: Contrasts between low- and high-temperature regimes. J Colloid Interface Sci 2021; 607:1571-1579. [PMID: 34587531 DOI: 10.1016/j.jcis.2021.09.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/03/2021] [Accepted: 09/04/2021] [Indexed: 11/30/2022]
Abstract
HYPOTHESIS Pressure dependence of contact angle is expected to be influenced by temperature. Nevertheless, the correlation of water contact angle with pressure is rarely investigated at high temperatures (over 100 ℃). EXPERIMENTS In this work, measurements of the contact angle and interfacial tension of water in N2 atmosphere were conducted at various pressures and temperatures (up to 17 MPa and 300 ℃). The experimental observations were elucidated based on the theory of surface thermodynamics. FINDINGS It was shown that the water-N2 interfacial tension linearly decreases with increasing the pressure, and that the pressure coefficient declines as temperature rises. The pressure dependence of the water contact angle was found to be different for the low- and high-temperature regimes: the water contact angle increases below 100 ℃, whereas an inverse variation occurs over 100 ℃. According to the theoretical analysis, the pressure dependence of both the water interfacial tension and contact angle is attributed to N2 adsorption on the surfaces of water and silicon. The variations in the water contact angle with pressure, including both the sign and magnitude, are actually the consequence of the changes of water-N2 and Si-N2 interfacial tensions manipulated by pressure and temperature.
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Affiliation(s)
- Jia-Wen Song
- Institute of Thermal Science and Power Systems, School of Energy Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China
| | - Li-Wu Fan
- Institute of Thermal Science and Power Systems, School of Energy Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China; State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China.
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34
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Fries MR, Skoda MWA, Conzelmann NF, Jacobs RMJ, Maier R, Scheffczyk N, Zhang F, Schreiber F. Bulk phase behaviour vs interface adsorption: Effects of anions and isotopes on β-lactoglobulin (BLG) interactions. J Colloid Interface Sci 2021; 598:430-443. [PMID: 33930747 DOI: 10.1016/j.jcis.2021.04.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/30/2021] [Accepted: 04/03/2021] [Indexed: 01/17/2023]
Abstract
HYPOTHESIS Protein adsorption is highly relevant in numerous applications ranging from food processing to medical implants. In this context, it is important to gain a deeper understanding of protein-protein and protein-surface interactions. Thus, the focus of this investigation is on the interplay of bulk properties and surface properties on protein adsorption. It was hypothesised that the type of solvent and ions in solution should significantly influence the protein's bulk and interface behaviour, which has been observed in literature and previous work for other net negatively charged, globular proteins such as bovine serum albumin (BSA). EXPERIMENTS The phase behaviour of β-lactoglobulin (BLG) with lanthanum chloride (LaCl3) and iodide (LaI3) in normal water H2O(l) and heavy water (D2O(l)) was established via optical microscopy and ultraviolet-visible spectroscopy. The formation of an adsorption layer and its properties such as thickness, density, structure, and hydration was investigated via neutron reflectivity, quartz-crystal microbalance with dissipation, and infra-red measurements. FINDINGS β-lactoglobulin does not show significant anion-induced or isotope-induced effects - neither in bulk nor at the solid-liquid interface, which deviates strongly from the behaviour of bovine serum albumin. We also provide a comprehensive discussion and comparison of protein-specific bulk and interface behaviour between bovine serum albumin and β-lactoglobulin dependent on anion, cation, solvent, and substrate properties. These findings pave the way for understanding the transition from adsorption to crystallisation.
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Affiliation(s)
- Madeleine R Fries
- Institute for Applied Physics, University of Tübingen, 72076 Tübingen, Germany.
| | - Maximilian W A Skoda
- ISIS Facility, STFC, Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom.
| | - Nina F Conzelmann
- Institute for Applied Physics, University of Tübingen, 72076 Tübingen, Germany.
| | - Robert M J Jacobs
- Department for Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom.
| | - Ralph Maier
- Institute for Applied Physics, University of Tübingen, 72076 Tübingen, Germany.
| | - Niels Scheffczyk
- Institute for Applied Physics, University of Tübingen, 72076 Tübingen, Germany.
| | - Fajun Zhang
- Institute for Applied Physics, University of Tübingen, 72076 Tübingen, Germany.
| | - Frank Schreiber
- Institute for Applied Physics, University of Tübingen, 72076 Tübingen, Germany.
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35
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Bhatt B, Gupta S, Sharma M, Khare K. De wetting of non-polar thin lubricating films underneath polar liquid drops on slippery surfaces. J Colloid Interface Sci 2021; 607:530-537. [PMID: 34509731 DOI: 10.1016/j.jcis.2021.08.211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 08/30/2021] [Accepted: 08/31/2021] [Indexed: 11/28/2022]
Abstract
HYPOTHESIS The stability of thin lubricating fluid-coated slippery surfaces depends on the surface energy of the underlying solid surface. High energy solid surfaces coated with thin lubricating oil lead to the dewetting of the oil films upon depositing aqueous drops on them. Hence such surfaces are very suitable to investigate dewetting of thick films (thickness > 500 nm), which otherwise is not possible using a conventional dewetting system. EXPERIMENTS Lubricating films of different thicknesses are coated on hydrophilic solid surfaces, and glycerol drops are deposited on them. Fluorescence imaging of lubricating films and macroscopic wetting behavior of glycerol drops are analyzed to understand the dewetting phenomenon. FINDINGS Underneath lubricating films undergo initial thinning and subsequently dewet. The dewetting dynamics during hole nucleation and growth and the final pattern of the dewetted oil droplets depend strongly on the thickness of the lubricating films. Ultrathin films dewet spontaneously via homogeneous nucleation, whereas thicker films dewet via heterogeneous nucleation. During dewetting, the apparent contact angle and radius of glycerol drops follow universal scaling behavior.
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Affiliation(s)
- Bidisha Bhatt
- Department of Physics, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Shivam Gupta
- Department of Physics, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Meenaxi Sharma
- Department of Physics, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Krishnacharya Khare
- Department of Physics, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India.
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36
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Stasic JN, Pficer JK, Milicic B, Puač N, Miletic V. Effects of non-thermal atmospheric plasma on dentin wetting and adhesive bonding efficiency: Systematic review and meta-analysis. J Dent 2021; 112:103765. [PMID: 34363890 DOI: 10.1016/j.jdent.2021.103765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/20/2021] [Accepted: 07/30/2021] [Indexed: 11/26/2022] Open
Abstract
OBJECTIVES This systematic review and meta-analysis evaluated the effects of non-thermal atmospheric plasma (NTAP) treatment on dentin wetting and adhesive-dentin bond strength. DATA/SOURCES This report followed the PRISMA 2020 statement. Two reviewers conducted literature search of MEDLINE, Web of Science and Scopus databases up to the end of November 2020. Included in vitro studies compared the effect of NTAP on treated dentin of non-carious, intact, extracted human third molar teeth with different control groups. Studies with no adequate methods, missing data, lack of control group, or those using animal teeth were excluded. The random effects model was used to summarize the treatment effect with standardized mean difference (SMD) and 95% CI. Risk of bias was assessed using the custom Cochrane Collaboration's tool. STUDY SELECTION/RESULTS Seventeen studies met inclusion criteria. The effects on dentin wetting were reported in favor of NTAP (SMD -5.38; 95% CI [-6.97, -3.78]; p<0.00001; I2=81%). Regarding adhesive-dentin bond strength, statistically significant differences between the NTAP and control group were in favor of NTAP in the short-term (SMD 1.92; 95%CI [1.35, 2.50]; p<0.00001; I2=97%), and long-term (SMD 3.28; 95%CI [2.46, 4.09]; p<0.00001; I2=97%). A limitation of meta-analysis is moderate heterogeneity caused by methodological differences and lack of data, which was evaluated through risk of bias and sensitivity analysis. CONCLUSIONS NTAP substantially improves dentin wetting and adhesive-dentin bond strength with 30 seconds exposure time and up to 10 mm tip-to-surface distances being sufficient for positive NTAP effects on bonding efficiency. FUNDING ON172207 and III41008 from the Ministry of Education, Science and Technological Development, Republic of Serbia. NP is funded by MESTD grant number 451-03-68/2020-14/200024. CLINICAL SIGNIFICANCE This systematic review and meta-analysis substantiate potential applicability of NTAP treatment of dentin in improving adhesive bonding clinically. Further research should be based on the optimized parameters such as time and distance with additional refinement of NTAP power.
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Affiliation(s)
- Jovana N Stasic
- DentalNet Research Group, School of Dental Medicine, University of Belgrade, Belgrade, Serbia
| | - Jovana Kuzmanovic Pficer
- Department for Medical Statistics and Informatics, School of Dental Medicine, University of Belgrade, Belgrade, Serbia
| | - Biljana Milicic
- Department for Medical Statistics and Informatics, School of Dental Medicine, University of Belgrade, Belgrade, Serbia
| | - Nevena Puač
- Institute of Physics, University of Belgrade, Pregrevica 118, Belgrade, Serbia
| | - Vesna Miletic
- Sydney Dental School, Faculty of Medicine and Health, The University of Sydney, Surry Hills 2010, Australia.
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Zhao J, Wu X, Ning L, Zhang J, Han C, Li Y. Wetting of aluminium and carbon interface during preparation of Al-Ti-C grain refiner under ultrasonic field. Ultrason Sonochem 2021; 76:105633. [PMID: 34198126 PMCID: PMC8254042 DOI: 10.1016/j.ultsonch.2021.105633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 05/25/2021] [Accepted: 06/14/2021] [Indexed: 06/13/2023]
Abstract
In the preparation of an Al-Ti-C grain refiner under an ultrasonic field, the mechanism of the wetting behaviour between Al and C was systematically investigated. The results demonstrated that the wetting behaviour was mainly dependent on the wetting of the Al melt on graphite under the ultrasonic field (physical wetting) and the formation and mass transfer of TiC (reactive wetting). The diffusion of Ti atoms and their adsorption around the graphite could contribute to the wetting of Al-C. TiC particles were formed under the high temperature caused by the cavitation effect, and they detached from the interface due to the sound pressure, which resulted in consistently sufficient contact on the wetting interface. Moreover, the wetting and spreading behaviour of the Al melt on graphite under an ultrasonic field were numerically simulated, strongly manifesting that the ultrasonic field could facilitate the wetting of the Al-C interface.
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Affiliation(s)
- Jingtao Zhao
- School of Materials Science and Engineering, Northeastern University, 11 Wenhua Road, Shenyang 110819, PR China; Key Laboratory of Lightweight Structural Materials, Liaoning Province, PR China
| | - Xiaoyu Wu
- School of Materials Science and Engineering, Northeastern University, 11 Wenhua Road, Shenyang 110819, PR China; Key Laboratory of Lightweight Structural Materials, Liaoning Province, PR China
| | - Liping Ning
- School of Materials Science and Engineering, Northeastern University, 11 Wenhua Road, Shenyang 110819, PR China; Key Laboratory of Lightweight Structural Materials, Liaoning Province, PR China
| | - Junjia Zhang
- School of Materials Science and Engineering, Northeastern University, 11 Wenhua Road, Shenyang 110819, PR China; Key Laboratory of Lightweight Structural Materials, Liaoning Province, PR China
| | - Chao Han
- School of Metallurgy, Northeastern University, Shenyang 110819, PR China
| | - Yinglong Li
- School of Materials Science and Engineering, Northeastern University, 11 Wenhua Road, Shenyang 110819, PR China; Key Laboratory of Lightweight Structural Materials, Liaoning Province, PR China.
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Akbari R, Antonini C. Contact angle measurements: From existing methods to an open-source tool. Adv Colloid Interface Sci 2021; 294:102470. [PMID: 34186300 DOI: 10.1016/j.cis.2021.102470] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 06/18/2021] [Accepted: 06/18/2021] [Indexed: 12/19/2022]
Abstract
Contact angle measurement is an effective way to investigate solid surface properties. The introduction of low-cost digital cameras, as well as software and libraries for image analysis, has made contact angle measurement potentially accessible to every laboratory. In this review, we provide a comparison of the main methods developed to evaluate contact angle from digital images, including the so-called Young-Laplace method, the circle and polynomial fittings, as well as the mask method. All methods have been implemented and compared analyzing virtual and real drop images in an open-source software, Dropen, developed as an app in MATLAB environment. The code enables single image analysis evaluation, for the robust automatic identification of the contact points and contact angle evaluation, with the goal of minimizing user inputs, automatizing the process and facilitating measurements for all users, from less experienced to advanced wetting experts. Dropen and its code are made available at BOA, the Bicocca Open Access public repository, for use and further development.
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Song JW, Fan LW. Unraveling the synergistic effects of solid surface material and temperature on the contact angle of water under an elevated pressure: An experimental study. J Colloid Interface Sci 2021; 605:163-172. [PMID: 34311311 DOI: 10.1016/j.jcis.2021.07.042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/06/2021] [Accepted: 07/07/2021] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS In terms of the Young's equation, the temperature dependence of liquid-solid contact angle is affected by the surface material, so the wetting behavior could be tuned by both changing the temperature and surface material. However, the synergistic effects of surface material and temperature on the water contact angle remain unclear, especially at elevated temperatures. EXPERIMENTS In this study, a systematic characterization of water contact angle against various smooth metallic and nonmetallic surfaces was conducted for temperatures up to 300 ℃ in a high-pressure chamber at 15 MPa. The measured results were finally compared with the predictions made by the sharp-kink approximation model. FINDINGS Not surprisingly, it was observed the temperature-dependent water contact angle is sensitive to the type of solid surface. The temperature coefficients and critical temperature points on the contact-angle-temperature curves can be manipulated by altering the surface material. However, the influence of surface material is weakened by raising temperature, thus leading to the nearly consistent temperature-dependent water contact angle over 120℃. Additionally, the necessity of investigating the internal flows within the water drops was highlighted to unravel the positive temperature correlation of the water contact angle at high temperatures, in view of the presence of non-spherical-cap-shaped drops.
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Affiliation(s)
- Jia-Wen Song
- Institute of Thermal Science and Power Systems, School of Energy Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China
| | - Li-Wu Fan
- Institute of Thermal Science and Power Systems, School of Energy Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China; State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China.
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Díaz D, Nickel O, Moraga N, Catalán RE, Retamal MJ, Zelada H, Cisternas M, Meißner R, Huber P, Corrales TP, Volkmann UG. How water wets and self-hydrophilizes nanopatterns of physisorbed hydrocarbons. J Colloid Interface Sci 2021; 606:57-66. [PMID: 34388573 DOI: 10.1016/j.jcis.2021.07.121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 07/22/2021] [Accepted: 07/23/2021] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS Weakly bound, physisorbed hydrocarbons could in principle provide a similar water-repellency as obtained by chemisorption of strongly bound hydrophobic molecules at surfaces. EXPERIMENTS Here we present experiments and computer simulations on the wetting behaviour of water on molecularly thin, self-assembled alkane carpets of dotriacontane (n-C32H66 or C32) physisorbed on the hydrophilic native oxide layer of silicon surfaces during dip-coating from a binary alkane solution. By changing the dip-coating velocity we control the initial C32 surface coverage and achieve distinct film morphologies, encompassing homogeneous coatings with self-organised nanopatterns that range from dendritic nano-islands to stripes. FINDINGS These patterns exhibit a good water wettability even though the carpets are initially prepared with a high coverage of hydrophobic alkane molecules. Using in-liquid atomic force microscopy, along with molecular dynamics simulations, we trace this to a rearrangement of the alkane layers upon contact with water. This restructuring is correlated to the morphology of the C32 coatings, i.e. their fractal dimension. Water molecules displace to a large extent the first adsorbed alkane monolayer and thereby reduce the hydrophobic C32 surface coverage. Thus, our experiments evidence that water molecules can very effectively hydrophilize initially hydrophobic surfaces that consist of weakly bound hydrocarbon carpets.
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Affiliation(s)
- Diego Díaz
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile; Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Ole Nickel
- Hamburg University of Technology, Institute of Polymers and Composites, 21073 Hamburg, Germany
| | - Nicolás Moraga
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
| | - Rodrigo E Catalán
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
| | - María José Retamal
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
| | - Hugo Zelada
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
| | - Marcelo Cisternas
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
| | - Robert Meißner
- Hamburg University of Technology, Institute of Polymers and Composites, 21073 Hamburg, Germany; Helmholtz-Zentrum Hereon, Institute of Surface Science, 21494 Geesthacht, Germany
| | - Patrick Huber
- Hamburg University of Technology, Institute for Materials and X-Ray Physics, 21073 Hamburg, Germany; Deutsches Elektronen-Synchrotron DESY, Centre for X-Ray and Nano Science CXNS, 22603 Hamburg, Germany; University of Hamburg, Centre for Hybrid Nanostructures CHyN, 22607 Hamburg, Germany.
| | - Tomas P Corrales
- Departamento de Física, Universidad Técnica Federico Santa María, Valparaiso 2390123, Chile.
| | - Ulrich G Volkmann
- Instituto de Física, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile; Centro de Investigación en Nanotecnología y Materiales Avanzados (CIEN-UC), Pontificia Universidad Católica de Chile, Santiago 7820436, Chile.
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41
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Savulescu GC, Rücker M, Scanziani A, Pini R, Georgiadis A, Luckham PF. Atomic force microscopy for the characterisation of pinning effects of seawater micro-droplets in n-decane on a calcite surface. J Colloid Interface Sci 2021; 592:397-404. [PMID: 33689984 DOI: 10.1016/j.jcis.2021.02.070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 01/28/2021] [Accepted: 02/15/2021] [Indexed: 10/22/2022]
Abstract
HYPOTHESIS Roughness is an important parameter in applications where wetting needs to be characterized. Micro-computed tomography is commonly used to characterize wetting in porous media but the main limitation of this approach is the incapacity to identify nanoscale roughness. Atomic force microscopy, AFM, however, has been used to characterize the topography of surfaces down to the molecular scale. Here we investigate the potential of using AFM to characterize wetting behavior at the nanoscale. EXPERIMENTS Droplets of water on cleaved calcite under decane were imaged using quantitative imaging QI atomic force microscopy where a force-distance curve is obtained at every pixel. FINDINGS When the AFM tip passed through the water droplet surface, an attraction was observed due to capillary effects, such that the thickness of the water film was estimated and hence the profile of the droplet obtained. This enables parameters such as the contact angle and contact angle distribution to be obtained at a nanometer scale. The contact angles around the 3-phase contact line are found to be quasi-symmetrically distributed between 10-30°. A correlation between the height profile of the surface and contact angle distribution demonstrates a quasi-proportional relationship between roughness on the calcite surface and contact angle.
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Affiliation(s)
- G C Savulescu
- Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - M Rücker
- Chemical Engineering, Imperial College London, SW7 2AZ, UK; Mechanical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands.
| | - A Scanziani
- Earth Science and Engineering, Imperial College London, SW7 2AZ, UK
| | - R Pini
- Chemical Engineering, Imperial College London, SW7 2AZ, UK
| | - A Georgiadis
- Chemical Engineering, Imperial College London, SW7 2AZ, UK; Shell Global Solutions International B.V., 2288 GS Rijswijk, The Netherlands
| | - P F Luckham
- Chemical Engineering, Imperial College London, SW7 2AZ, UK
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Mura E, Ding Y. Nucleation of melt: From fundamentals to dispersed systems. Adv Colloid Interface Sci 2021; 289:102361. [PMID: 33561567 DOI: 10.1016/j.cis.2021.102361] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 01/12/2021] [Accepted: 01/13/2021] [Indexed: 11/28/2022]
Abstract
The most evident aspects of a first order transition of a system from an old to a new phase, are the presence of a discontinuity at the interface between both phases and the thermal effects related to the latent heat exchanged with the surrounding environment. These effects are the result of a sequence of events promoted by thermodynamic conditions persisting over the equilibrium in a metastable state. The breakdown of metastability is promoted by infinitesimal energy fluctuations resulting in the germination of clusters of the new phase that can grow to a critical size (nucleus) and then develop or vanish. Examples of these sequences are common in various technological fields such as combustion, food processing, pharmaceutical manufacturing, condensation, and phase change heat transfer, etc. This work aims to highlight a logical path that leads the readers from the fundamental phenomenology to the most intricated aspects of the nucleation within dispersed systems such as oil-in-water emulsions. Differences between the homogeneous and heterogeneous mechanisms are, under the light of the Classical Nucleation Theory (CNT), presented in bulk and confined systems until defining a minimum confinement size. By collecting insights coming from a rich scientific literature mostly focused on the stability of emulsified systems, the discussion is then on the aspects related to the surface related mechanisms. Two main aspects are then considered: a) the wettability of the nucleating cluster by the surrounding melt; b) the affinity between the adsorbed layer, where a surfactant is located, and the oil melt phase (mainly n-alkanes and triacylglycerols with different moieties). In cases where nucleation is dominating over the dewetting of the nucleus, the contact angle can be considered as a constant value. The affinity in terms of molecular features between the surfactant and the oil phase can promote the template effect. Several factors seem to play a role in this interaction such as the thermal characteristics of the surfactant and comparable dimensions between the molecule (or fractions) of the dispersed compound and the tail of the surfactant.
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Affiliation(s)
- Ernesto Mura
- Global Energy Interconnection Research Institute Europe GmbH, Kantstr. 162, 10623 Berlin, Germany.
| | - Yulong Ding
- Birmingham Centre for Energy Storage & School of Chemical Engineering, Univ. of Birmingham, B15 2TT, UK
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43
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Baumli P, D'Acunzi M, Hegner KI, Naga A, Wong WSY, Butt HJ, Vollmer D. The challenge of lubricant-replenishment on lubricant-impregnated surfaces. Adv Colloid Interface Sci 2021; 287:102329. [PMID: 33302056 DOI: 10.1016/j.cis.2020.102329] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 11/22/2020] [Accepted: 11/23/2020] [Indexed: 11/18/2022]
Abstract
Lubricant-impregnated surfaces are two-component surface coatings. One component, a fluid called the lubricant, is stabilized at a surface by the second component, the scaffold. The scaffold can either be a rough solid or a polymeric network. Drops immiscible with the lubricant, hardly pin on these surfaces. Lubricant-impregnated surfaces have been proposed as candidates for various applications, such as self-cleaning, anti-fouling, and anti-icing. The proposed applications rely on the presence of enough lubricant within the scaffold. Therefore, the quality and functionality of a surface coating are, to a large degree, given by the extent to which it prevents lubricant-depletion. This review summarizes the current findings on lubricant-depletion, lubricant-replenishment, and the resulting understanding of both processes. A multitude of different mechanisms can cause the depletion of lubricant. Lubricant can be taken along by single drops or be sheared off by liquid flowing across. Nano-interstices and scaffolds showing good chemical compatibility with the lubricant can greatly delay lubricant depletion. Often, depletion of lubricant cannot be avoided under dynamic conditions, which warrants lubricant-replenishment strategies. The strategies to replenish lubricant are presented and range from spraying or stimuli-responsive release to built-in reservoirs.
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Affiliation(s)
- Philipp Baumli
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Maria D'Acunzi
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Katharina I Hegner
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Abhinav Naga
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - William S Y Wong
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Hans-Jürgen Butt
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Doris Vollmer
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
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44
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Labonte D, Robinson A, Bauer U, Federle W. Disentangling the role of surface topography and intrinsic wettability in the prey capture mechanism of Nepenthes pitcher plants. Acta Biomater 2021; 119:225-233. [PMID: 33189952 DOI: 10.1016/j.actbio.2020.11.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 10/15/2020] [Accepted: 11/03/2020] [Indexed: 11/27/2022]
Abstract
Nepenthes pitcher plants capture prey with leaves specialised as pitfall traps. Insects are trapped when they 'aquaplane' on the pitcher rim (peristome), a surface structured with macroscopic and microscopic radial ridges. What is the functional significance of this hierarchical surface topography? Here, we use insect pad friction measurements, photolithography, wetting experiments and physical modelling to demonstrate that the ridges enhance the trap's efficacy by satisfying two functional demands on prey capture: Macroscopic ridges restrict lateral but enhance radial spreading of water, thereby creating continuous slippery tracks which facilitate prey capture when little water is present. Microscopic ridges, in turn, ensure that the water film between insect pad and peristome remains stable, causing insects to aquaplane. In combination, the hierarchical ridge structure hence renders the peristome wettable, and water films continuous, so avoiding the need for a strongly hydrophilic surface chemistry, which would compromise resistance to desiccation and attract detrimental contamination.
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45
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Kamp M, de Nijs B, Baumberg JJ, Scherman OA. Contact angle as a powerful tool in anisotropic colloid synthesis. J Colloid Interface Sci 2021; 581:417-426. [PMID: 32771750 DOI: 10.1016/j.jcis.2020.07.074] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 06/27/2020] [Accepted: 07/16/2020] [Indexed: 11/28/2022]
Abstract
Nucleation and growth is a technique widely used to prepare colloids, in which droplets are adsorbed onto substrate particles. Changing the contact angle of the substrates can greatly alter the morphology of the product particles. Here, we investigate the nucleation and growth of 3-methacryloxypropyltrimethoxysilane (MPTMS) both onto Stöber spheres and onto (cross-linked) MPTMS* spheres. The former results in 'snowman' particles with a cap-shaped MPTMS* compartment, and we show that their morphology is highly controllable via the MPTMS content in the reaction mixture. The contact angle of the MPTMS* compartment decreases with droplet diameter, suggesting that this wetting process is affected not only by surface tension but also by line tension. In contrast to Stöber spheres, MPTMS* substrate particles yield highly reproducible and tuneable 'engulfed-sphere' colloids with an internal reference axis (but a homogeneous mass distribution). These engulfed-sphere particles can be fully index-matched for confocal microscopy on account of their homogeneous refractive index. Suitable index-matching mixtures of polar and of low-polar media are presented, where cyclohexyl iodide (CHI) is introduced as a new medium for colloids of high refractive index. Finally, the index-matched engulfed-sphere colloids are self-assembled into (close-packed and long-range) plastic phases, and the particles' rotational diffusion inside the crystal phases is tracked via confocal microscopy.
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Affiliation(s)
- Marlous Kamp
- Melville Laboratory for Polymer Synthesis, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, United Kingdom; NanoPhotonics Centre, Department of Physics, University of Cambridge, Cambridge, CB3 0HE, United Kingdom.
| | - Bart de Nijs
- NanoPhotonics Centre, Department of Physics, University of Cambridge, Cambridge, CB3 0HE, United Kingdom.
| | - Jeremy J Baumberg
- NanoPhotonics Centre, Department of Physics, University of Cambridge, Cambridge, CB3 0HE, United Kingdom.
| | - Oren A Scherman
- Melville Laboratory for Polymer Synthesis, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, United Kingdom.
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46
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Fan J, De Coninck J, Wu H, Wang F. A generalized examination of capillary force balance at contact line: On rough surfaces or in two-liquid systems. J Colloid Interface Sci 2020; 585:320-327. [PMID: 33302048 DOI: 10.1016/j.jcis.2020.11.100] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/24/2020] [Accepted: 11/25/2020] [Indexed: 01/01/2023]
Abstract
We investigate the capillary force balance at the contact line on rough solid surfaces and in two-liquid systems. Our results confirm that solid-liquid interactions perpendicular to the interface have a significant influence on the lateral component of the capillary force exerted on the contact line. Surface roughness of the solid substrate reduces the mobility of liquid and alters how the perpendicular solid-liquid interactions transfer into a force acting parallel to the interface. A quantitative relation between surface roughness and the transfer strategy is proposed. Moreover, when a liquid is in coexistence with another immiscible liquid on a solid, the capillary forces exerted on liquids of both sides are involved in our theoretical model. The contact angle can be predicted by calculating three interfacial tensions. These arguments are then verified by molecular dynamics simulations. Our findings set up the generalized theoretical framework for the capillary force balance at the contact line and broaden its application in more realistic scenarios.
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Affiliation(s)
- JingCun Fan
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, CAS Center for Excellence in Complex System Mechanics, University of Science and Technology of China, Hefei 230027, China
| | - Joël De Coninck
- Laboratory of Surface and Interfacial Physics (LPSI), University of Mons, 7000 Mons, Belgium
| | - HengAn Wu
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, CAS Center for Excellence in Complex System Mechanics, University of Science and Technology of China, Hefei 230027, China.
| | - FengChao Wang
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, CAS Center for Excellence in Complex System Mechanics, University of Science and Technology of China, Hefei 230027, China.
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47
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Cape JL, Pluntze AM, Nelson ML, Seymour JD, Miller WK, Dower AM, Buchanan SS. Mechanisms of water permeation and diffusive API release from stearyl alcohol and glyceryl behenate modified release matrices. Int J Pharm 2020; 589:119819. [PMID: 32871217 DOI: 10.1016/j.ijpharm.2020.119819] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 08/07/2020] [Accepted: 08/23/2020] [Indexed: 10/23/2022]
Abstract
This work aims to develop complimentary analytical tools for lipid formulation selection that offer insights into the mechanisms of in-vitro drug release for solid lipid modified release excipients. Such tools are envisioned to aide and expedite the time consuming process of formulation selection and development. Two pharmaceutically relevant solid lipid excipients are investigated, stearyl alcohol and glyceryl behenate, which are generally known to exhibit faster and slower relative release rates, respectively. Nuclear magnetic resonance spectroscopy and diffusometry are used, along with water uptake and dissolution experiments to help distinguish between two proposed in-vitro release mechanisms for crystalline caffeine from these matrices: 1) rate limiting movement of the wetting front through the particle, and 2) rate limiting diffusive release of the active from the wetted particle. Findings based on water permeation rates, API diffusion coefficients and kinetic modeling suggest that the rate limiting steps for caffeine release from these matrices are different, with stearyl alcohol being co-rate limited by movement of the wetting front and diffusive release of API, whereas glyceryl behenate is more strictly limited by diffusive release of API from the wetted matrix. A Peclet-like number is proposed to describe the different regimes of rate limitation for drug release. NMR spectroscopy and diffusometry are demonstrated to be useful tools for elucidating mechanisms of API release from crystalline drug/lipid mixtures and have significant potential value as screening tools in MR formulation development.
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Affiliation(s)
- Jonathan L Cape
- Research and Development, Lonza Pharma, Biotech and Nutrition, Bend, OR, USA.
| | - Amanda M Pluntze
- Research and Development, Lonza Pharma, Biotech and Nutrition, Bend, OR, USA
| | - Madison L Nelson
- Department of Physics, Montana State University, Bozeman, MT 59717-3920, USA
| | - Joseph D Seymour
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, 59717-3920, USA
| | - Warren K Miller
- Research and Development, Lonza Pharma, Biotech and Nutrition, Bend, OR, USA
| | - April M Dower
- Research and Development, Lonza Pharma, Biotech and Nutrition, Bend, OR, USA
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48
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Udukumburage RS, Gallage C, Dawes L, Gui Y. Determination of the hydraulic conductivity function of grey Vertosol with soil column test. Heliyon 2020; 6:e05399. [PMID: 33204879 PMCID: PMC7649276 DOI: 10.1016/j.heliyon.2020.e05399] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 08/24/2020] [Accepted: 10/28/2020] [Indexed: 11/19/2022] Open
Abstract
Expansive soils exhibit swell-shrink behaviour in wet-dry periods resulting in distresses on light-weight structures founded on/in them. Therefore, it is essential to investigate the climate-ground interaction when designing structures on expansive soils. Laboratory-based models are preferred to investigate the climatic-ground interaction of expansive soils due to the uncontrollability of the boundary conditions and expenses associated with field monitoring. More flexibility in analysing the climatic-induced hydraulic responses in expansive soils can be achieved by finite element modelling of data from physical model tests. However, these laboratory-based models regularly encounter the effects of boundary flaw, preferential flow paths and entrapped air that needs to be accounted for when numerically simulated. In this study, the authors aim to numerically model the hydraulic responses in an instrumented Vertosol soil column (ISC) under controlled laboratory conditions. The effects of the preferential flow paths and boundary flaws were incorporated into a modified hydraulic conductivity as a practical approach to model the hydraulic responses in ISC. Influence of the entrapped air was rectified by a suitable correction factor. These findings present a practical method for geotechnical practitioners to accurately estimate the suction and volumetric water content profiles in laboratory-based expansive soil model tests.
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49
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Rajwade K, Barrios AC, Garcia-Segura S, Perreault F. Pore wetting in membrane distillation treatment of municipal wastewater desalination brine and its mitigation by foam fractionation. Chemosphere 2020; 257:127214. [PMID: 32505039 DOI: 10.1016/j.chemosphere.2020.127214] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 05/22/2020] [Accepted: 05/23/2020] [Indexed: 06/11/2023]
Abstract
Reverse Osmosis (RO) desalination is an important step of wastewater reuse as it can remove salts and trace contaminants. However, RO also generates high salinity brines that need to be dealt with. Membrane distillation (MD), a process largely unaffected by salinity, provides a way to treat desalination brines up to high water recovery and has been proposed as a solution for RO brine management. However, pore wetting of membranes in MD is one of the major hurdles that prevents its implementation in wastewater treatment systems, as amphiphilic organic compounds present in wastewater can lead to pore wetting and loss of selectivity over time. The objective of this study was to identify a pre-treatment strategy to prevent wetting in MD treatment of municipal wastewater RO brines. We compared three pre-treatments with different separation or removal mechanisms: foam fractionation, advanced oxidation, and ultrafiltration. We evaluated membrane wetting by measuring the change in conductivity in the distillate and identified the most effective pre-treatment to prevent wetting in MD. The results show that wetting is prevented by pre-treating the brine with foam fractionation. The effectiveness of foam fractionation as a wetting control strategy was confirmed for a high wetting propensity synthetic water using sodium dodecyl sulfate as a model wetting compound. Finally, the effect of the pre-treatments on the desalination brine was evaluated to understand the nature of the compounds removed by each treatment. The results of this study will help implement MD as a treatment process for desalination brines in municipal wastewater reuse systems.
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Affiliation(s)
- Kimya Rajwade
- School of Sustainable Engineering and the Built Environment, Arizona State University, United States; Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, Arizona State University, Tempe, AZ, United States
| | - Ana C Barrios
- School of Sustainable Engineering and the Built Environment, Arizona State University, United States; Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, Arizona State University, Tempe, AZ, United States
| | - Sergi Garcia-Segura
- School of Sustainable Engineering and the Built Environment, Arizona State University, United States; Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, Arizona State University, Tempe, AZ, United States
| | - François Perreault
- School of Sustainable Engineering and the Built Environment, Arizona State University, United States; Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, Arizona State University, Tempe, AZ, United States.
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Zdziennicka A, Jańczuk B. Modification of adsorption, aggregation and wetting properties of surfactants by short chain alcohols. Adv Colloid Interface Sci 2020; 284:102249. [PMID: 32987295 DOI: 10.1016/j.cis.2020.102249] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 08/20/2020] [Accepted: 08/20/2020] [Indexed: 11/21/2022]
Abstract
The adsorption of methanol, ethanol and propan-1-ol at the solution-air and solid-solution interfaces, their aggregation in the aqueous media as well as wetting properties regarding their applications as additives or co-surfactants in the surfactants aqueous solution were discussed based on the literature data. Mutual influence of alcohols and surfactants on the solution-air and solid-solution interface tension was considered. For this purpose there were used different methods allowing to describe or predict changes of water surface tension as a function of alcohols concentration. These, in turn, as a function of alcohol and/or surfactant concentration were also analyzed by means of the methods applied for prediction of surface tension of aqueous solution of the classical surfactants mixture. The same considerations related to the behaviour of alcohol and surfactant at the solid-solution and solution-air interfaces were made. To explain the behaviour of alcohols and surfactants mixture at the solution-air and solid-solution interfaces the components and parameters of water, alcohols, surfactants and solids surface tension as well as the Gibbs free energy changes during the adsorption process were taken into account. It was proved that wettability of some solids can be predicted based on alcohol and surfactants adsorption as well as surface tension components and parameters. As follows the mutual influence of alcohol and surfactant on their adsorption at the solution-air and solid-solution interfaces as well as on the wetting properties at the alcohol concentration from zero to its critical aggregation concentration (CAC) is different from that at its concentration higher than CAC.
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