The field of anti-bioadhesion also involves protein adsorption, bacterial adhesion, and cell culturing media, all of them wettability-dependent phenomena [ 52 ]. Moreover, polydimethylsiloxane PDMS surfaces with various sized-rugosities, superposed scale plates, submicron structures, and nanostructured and smooth surfaces, proved the highest effectiveness against blood platelet adhesion in superposed scale plate surface [ 53 ].
Antibacterial cellulose fibers modified with siloxanes and silver nanoparticles show durable activity against Escherichia coli and Staphylococcus aureus [ 54 ], while bactericidal action against Pseudomonas aeruginosa was discovered for fluoroalkyl silane-hydrophobized glass [ 55 ].
Condensed matter physics
Advantages of the method include lack of lateral contamination risks due to hydrophobic separative borders, efficiency, economic analysis method, the possibility of real-time screening, and noninvasive diagnosis [ 56 , 57 , 58 ]. Other high-impact applications of superhydrophobic surfaces include anti-icing , antireflective , and low friction properties, mostly popular in the marine and aviation transportation fields, mirrors, and lens industry [ 59 , 60 , 61 , 62 ].
These properties along with a low adhesion degree, a high contact angle, and a low sliding angle allow impurity collection, while rolling off represent desired characteristics for windshields, exterior windows, and solar panels [ 63 ]. Since metal corrosion is a contemporary problem, superhydrophobic anticorrosion treatments were developed: coating techniques microwave chemical vapor deposition, followed by immersion with fluorochloride silanes of magnesium alloys and substrate modifications Al with hydroxides, Zn immersed in superhydrophobic solutions , proving resistance against acids, alkaline, or saline solutions [ 64 ].
Closely following the corrosion issue is friction reduction , which is of interest in aeronautics and ships. The shark skin and the lotus leaf are models in designing continuous surface films with self-contained air bubbles, able to reduce laminar and turbulent liquid flow, lowering friction forces.
Moreover, recent progress includes high-pressure-resistant special surfaces, with a high impact in the submarine industry [ 65 ]. Prototypes of miniature robots which walk-in straight-line and function as water-pollutant monitors, displaying high transport capacities [ 66 , 67 ]. Interdisciplinary researches on surface extreme wettability will be continued by discussing an intrinsically superhydrophobic behavior, characteristic for versatile structures entitled liquid marbles. Liquid marbles are non-wettable structures, formed as a result of physical interactions between solid particles and a liquid drop.
The formations are in fact represented by a liquid core covered in a particle shell Figure 6 and exhibit a superhydrophobic-like behavior, without the intervention of surface modifications. When compared to plain water drops, the manufactured liquid marbles did not wet the support, due to the fact that the liquid-solid interface water-glass is replaced with a solid-solid interface Lycopodium particles-glass.
They resemble raindrops falling on lotus leaves and collecting dust particles while rolling off, as previously discussed The Lotus Effect [ 70 ]. The hydrophobic particle wall thickness varies depending on the particles, which are linked by van der Waals forces and distribute as mono- or a multilayers. Similar to superhydrophobic surfaces, liquid marbles can also exhibit special structural architectures, depending on their components.
The method is proposed as the model in designing spherical objects. Among liquid marbles with curious properties are the ones guided using electric fields which resemble Janus particles. They are obtained by forcing together two marbles with different shells, resulting in a bigger marble: half covered in carbon black and the other in Teflon Figure 8 [ 77 ].
They are resistant to high temperatures, float on water, but must be obtained in a diluted hydrochloric acid solution, as an unwanted reduction reaction takes place in air [ 79 ]. Cases of hydrophilic particle-covered liquid marbles are possible due to air trapped between particles, resulting in aggregates which cover the droplets [ 80 ]. When discussing liquid marbles obtaining procedures, the most popular manufacturing method is the droplet rolling in a powder bed, as previously presented.
Continuous research is developed concerning this domain since the proposed method is inefficient and time-consuming; irregularly covered marbles are formed and cannot be transposed at an industrial level.
- Account Options.
- Key Marketing Metrics: The 50+ Metrics Every Manager Needs to Know.
- World Economic Issues at the United Nations: Half a Century of Debate;
- E. coli Plasmid Vectors: Methods and Applications.
Methods including condensation and drop nucleation were recently reported: the liquid core is placed in a container, warmed by a heat source underneath. Hydrophobic particles Cab-O-Sil fumed silica and micronic-sized Teflon are distributed in a thin layer at the liquid-air interface.
Cluster Models for Surface and Bulk Phenomena | SpringerLink
As the liquid boils, vapors condense and are covered by the particles. Micronic liquid marbles are formed. Advantages of the method include industrially applicability of the technique and possibility to adapt conditions depending on the desired result [ 81 ]. Wrapping drops in transparent glass fibers, avoiding fluid evaporation, is a proposed design in developing new controlled drug release systems, water purification membranes [ 82 ]. Another automatized method is considered revolutionary by using instead of hydrophobic powders a superhydrophobic cloth of nanofibers.
The drop is covered after impacting the cloth, resulting in highly resistant liquid marbles, with no internal phase loss [ 83 ]. Regarding their formulation, liquid marbles are versatile structures. Experimentally formed liquid marbles exhibit slightly different properties compared to naturally formed ones.
Raindrops fall from big heights and get covered with particles due to internal currents and to kinetic energy [ 84 ]. Coalescence of the drops and possibility to engulf exterior objects may also be related to elasticity. As a result of applying exterior forces, two different liquid marbles connected through a glass bar undergo coalescence, forming a bigger structure and sharing a divided shell, as illustrated in Figure 10 a.
Experiments on PTFE-covered liquid marbles reveal surface aggregates, and multilayers are formed at the liquid-air interface, triggering wall thickening and shrinkage during evaporation. Thus, slow evaporation of water results in prolonged resistance of the microparticle-covered marbles, with emerging applications in microfluidics [ 90 ].
The explanation lies in the fact that heat generates shrinkage at the liquid-air interface in case of the uncovered drop, while solid particles block interface compression during drying. Marbles covered in a multilayered shell dry harder than uncovered drops, depending on the thickness of the particle layer. This phenomenon happens in normal conditions. In humid atmosphere, marbles maintain their shape many days while floating [ 94 ]. As expected, the deformation of the interface increases, consecutive to larger drops [ 95 ]. After floating investigations, self-propelling of liquid marbles became of interest, when an autonomous movement similar to Leidenfrost droplets was reported for water and alcohol marbles covered in extremely hydrophobic fumed silica.
Supports include Petri dishes with water, and straight-line movement was observed. The layer forms as ethanol evaporates from the core. The Marangoni flow is triggered by ethanol condensation on the water support surface. Thus, the marbles begin to move without rolling. Fumed silica and Teflon-covered Janus marbles present no black traces while moving [ 96 ]. Due to their versatile formulations and their special superhydrophobic-like properties, liquid marbles exhibit promising applications in various domains.
In the pharmaceutical domain, liquid marbles are known as precursors of hollow granules, microcapsules, and Pickering-like emulsions. Hollow granule formation is promoted by high drying temperatures, nanometric particles, and high binder concentrations. Moreover, liquid marbles are able to include low solubility and hydrophobic active ingredients, representing formulation alternatives in case of substance incompatibilities and targeted release drugs e. Neupane, C. Liu, et al. Bulk intergrowth of a topological insulator with a room-temperature ferromagnet.
Ji, J. Allred, N.
Ni, et al. B 85, Fermi-surface topology and low-lying electronic structure of the iron-based superconductor Ca10 Pt3As8 Fe2As2 5. Coexisting pseudogap, charge-transfer-gap, and Mott-gap energy scales in the resonant inelastic x-ray scattering spectra of electron-doped cuprate superconductors. Basak, T. Das, H.
Lin, et al. Spin-orbital ground states of superconducting doped topological insulators: A Majorana platform. B 83, Topological electronic structure in half-Heusler topological insulators. Lin, R. Markiewicz, et al. B 82, Qian, Y. Xia, L. Wray, et al. Half-Heusler ternary compounds as new multifunctional experimental platforms for topological quantum phenomena. Lin, L. Wray, Y.
chapter and author info
Development of ferromagnetism in the doped topological insulator Bi2- xMnxTe3. Hor, P. Roushan, H. Beidenkopf, et al. B 81, Xia, D. Qian, L. Intermediate dimensional character of charge transfer excitation modes in a two-leg cuprate ladder. Wray, D. Qian, D. Hsieh, et al. Magnetic excitations in triangular lattice NaCrO2. Hsieh, D.
- Stenting the Urinary System, Second Edition.
- Applications of Fibonacci numbers. : Volume 9 proceedings of the Tenth International research conference on Fibonacci numbers and their applications.
- Control of magnetic wave by ultrashort light pulses.