Measuring air layer volumes retained by submerged floating-ferns Salvinia and biomimetic superhydrophobic surfaces

• Matthias J. Mayser,
• Holger F. Bohn,
• Meike Reker and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2014, 5, 812–821, doi:10.3762/bjnano.5.93

• biomimetic applications like drag reduction in ship coatings of up to 30%. Here we present a novel method for measuring air volumes and air loss under water. We recorded the buoyancy force of the air layer on leaf surfaces of four different Salvinia species and on one biomimetic surface using a highly

• also allows to measure decrease or increase of air layers with high accuracy in real-time to understand dynamic processes. Keywords: air layer; biomimetic; drag reduction; functional surfaces; plastron; Salvinia effect; volume measurement; Introduction Since the description of hierarchically

• applications for these trapped air layers in the Cassie wetting regime have been proposed which include drag reducing ship coatings or fluid channels [22][23][24][25][26] with the capability of 30% drag reduction [27] and could provide high economic and ecologic value [28][29]. While superhydrophobic plant

The surface microstructure of cusps and leaflets in rabbit and mouse heart valves

• Xia Ye,
• Bharat Bhushan,
• Ming Zhou and
• Weining Lei

Beilstein J. Nanotechnol. 2014, 5, 622–629, doi:10.3762/bjnano.5.73

• adhesion, and drag reduction. Therefore, studying the surfaces of natural organisms is extremely important and significant. Moreover, results of this study could have a substantial effect on the manufacturing of artificial biological products. During the past decade, the special surface microstructures of

Exploring the retention properties of CaF₂ nanoparticles as possible additives for dental care application with tapping-mode atomic force microscope in liquid

• Matthias Wasem,
• Joachim Köser,
• Sylvia Hess,
• Enrico Gnecco and
• Ernst Meyer

Beilstein J. Nanotechnol. 2014, 5, 36–43, doi:10.3762/bjnano.5.4

• layer (hydrodynamic drag of water layer), but the intrinsic particle–sample interaction energies. The frequency distribution of the calculated power dissipated for each of the particles enables us to examine the chemical affinity between the calcium fluoride nanoparticles adsorbed on mica and on

Dynamic nanoindentation by instrumented nanoindentation and force microscopy: a comparative review

• Sidney R. Cohen and
• Estelle Kalfon-Cohen

Beilstein J. Nanotechnol. 2013, 4, 815–833, doi:10.3762/bjnano.4.93

• its behavior suspended in air [103]. A known reference was used for calibration, allowing them to measure storage and loss modulus with an ultrasonic contact technique utilizing the first three flexural modes. For measurements in any fluid, including air, there will be a drag force on the bulk

• cantilever. In liquid, this drag force is very significant. Mahaffy et al. recorded this force in an aqueous environment as the tip approached the surface, but before it made contact and thus comprised a noncontact measurement of the phase shift [104]. A combination of the two corrections was made in a study

• of viscoelastic behavior of cells [105]. In this work, the hydrodynamic drag of the cantilever was measured at varying heights above the surface, and in addition, the phase response of the AFM piezo was measured in contact with a stiff cantilever probe on a hard surface in air. These few examples

Nanoglasses: a new kind of noncrystalline materials

• Herbert Gleiter

Beilstein J. Nanotechnol. 2013, 4, 517–533, doi:10.3762/bjnano.4.61

• concentration at the interfaces of the FeSc nanoglass. This enhanced concentration may delay the interfacial delocalization. For example, in the case of Y–Fe nanocrystalline materials grain growth was found to cease due to the solute segregation to the interfaces [29][30][31] (“solute drag effect”) [32][33][34

Structural and thermoelectric properties of TMGa₃ (TM = Fe, Co) thin films

• Sebastian Schnurr,
• Ulf Wiedwald,
• Paul Ziemann,
• Valeriy Y. Verchenko and
• Andrei V. Shevelkov

Beilstein J. Nanotechnol. 2013, 4, 461–466, doi:10.3762/bjnano.4.54

• conclusion on the amorphous state of the presently discussed films has immediate implications on their thermoelectric behavior. First of all, the scattering of electrons is dominated by the static disorder rather than by phonons. As a consequence, phonon drag effects, which usually are responsible for strong

• temperature behavior with no indication for phonon drag peaks in the lower temperature range. Also the magnitude of the S(300 K)-values ranging between 4 and 8 μV/K are typical of high-resistance metallic glasses [16]. This clearly confirms the idea of amorphous rather than nanocrystalline structures for the

• (300 K)-values of only some μV/K are likely. However, in crystalline samples a possibly present phonon drag may give rise to more pronounced nonlinearities in the temperature dependence of the Seebeck coefficient. Thus, at this point we conclude that the thermoelectric behavior of our films as

Controlled deposition and combing of DNA across lithographically defined patterns on silicon

• Zeinab Esmail Nazari and
• Leonid Gurevich

Beilstein J. Nanotechnol. 2013, 4, 72–76, doi:10.3762/bjnano.4.8

• temperature. On a sufficiently functionalized substrate, the droplet produces a contact angle of ≈90°, which makes it easy to gently move the droplet along the surface. In this experiment, we used a plastic pipette tip to drag the droplet out of the substrate. Preparation of DNA–peptide conjugates was

Effect of spherical Au nanoparticles on nanofriction and wear reduction in dry and liquid environments

• Dave Maharaj and
• Bharat Bhushan

Beilstein J. Nanotechnol. 2012, 3, 759–772, doi:10.3762/bjnano.3.85

• drag. In experiments where electrostatic micromotors are operated in a liquid environment, there have been problems of excessive drag and damping, which limited operating speeds, due to the use of high viscosity (20–60 cSt) oils [24]. However, studies have also demonstrated that friction and wear can

Friction and durability of virgin and damaged skin with and without skin cream treatment using atomic force microscopy

• Bharat Bhushan,
• Si Chen and
• Shirong Ge

Beilstein J. Nanotechnol. 2012, 3, 731–746, doi:10.3762/bjnano.3.83

• caused by the change of cream film thickness. When cream is first applied to the skin surface, the cream cannot be absorbed immediately by the skin, and the cream liquid accumulates at the contact interface, resulting in a larger liquid height and greater viscous drag to motion. However, after several

Pulse-response measurement of frequency-resolved water dynamics on a hydrophilic surface using a Q-damped atomic force microscopy cantilever

• Masami Kageshima

Beilstein J. Nanotechnol. 2012, 3, 260–266, doi:10.3762/bjnano.3.29

• relax until it reaches a new equilibrium state. This effect leads to a lateral flow of the fluid and is detected as a long decay time of the cantilever position and hence a large apparent drag coefficient [31]. This lateral flow is considered to cause coupling between the longitudinal response of the

Analysis of fluid flow around a beating artificial cilium

• Mojca Vilfan,
• Gašper Kokot,
• Andrej Vilfan,
• Natan Osterman,
• Blaž Kavčič,
• Igor Poberaj and
• Dušan Babič

Beilstein J. Nanotechnol. 2012, 3, 163–171, doi:10.3762/bjnano.3.16

• combined the resistive-force theory to calculate the drag-force density along the cilium and the Blake tensor in the far-field approximation to calculate the volume fluid flow. They modelled the cilium as a slender rod of length L and radius a, moving along a cone with a semicone angle ψ, tilted by the

• angle θ from the vertical position. Their expression for the generated volume flow reads as where CN is the transverse drag coefficient from the resistive force theory and η the water viscosity. Performing numerical simulations as described in [21] and comparing the calculated volume flow rate with

Dynamics of capillary infiltration of liquids into a highly aligned multi-walled carbon nanotube film

• Sławomir Boncel,
• Krzysztof Z. Walczak and
• Krzysztof K. K. Koziol

Beilstein J. Nanotechnol. 2011, 2, 311–317, doi:10.3762/bjnano.2.36

• liquid in a rate that can be linearly correlated to dynamic viscosity of the liquid (η). The experimental results follow the classical theory of capillarity for a steady process (Lucas–Washburn law), where the nanoscale capillary force, here supported by gravity, is compensated by viscous drag. This most

• law refers to a quasi-steady state of the liquid flow by the capillary action, where capillary force, expressed by the above thermodynamic parameters, contact angle (θ) and surface tension (γL), is compensated by gravity and viscous drag [35]. The height of the meniscus of the infiltrating liquid

Determination of object position, vortex shedding frequency and flow velocity using artificial lateral line canals

• Adrian Klein and
• Horst Bleckmann

Beilstein J. Nanotechnol. 2011, 2, 276–283, doi:10.3762/bjnano.2.32

• lateral line canals open to the environment through a series of pores. In teleosts, CNs are located halfway between neighbouring canal pores. Drag forces, resulting from fluid motions induced inside the canal by pressure fluctuation outside of the canal, stimulate CNs. In general, CNs respond (up to a

Superhydrophobic surfaces of the water bug Notonecta glauca: a model for friction reduction and air retention

• Petra Ditsche-Kuru,
• Erik S. Schneider,
• Jan-Erik Melskotte,
• Martin Brede,
• Alfred Leder and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2011, 2, 137–144, doi:10.3762/bjnano.2.17

• extremely interesting as a biomimetic model for low friction fluid transport or drag reduction on ship hulls. Keywords: air film; aquatic insects; backswimmer; drag reduction; superhydrophobic surfaces; Introduction Superhydrophobic surfaces are of great economic interest because of their amazing

• interesting property of superhydrophobic surfaces, which did not receive so much attention in the past, is the ability to retain an air film while submerged under water. This air film cover can reduce drag of solid bodies sliding through water [8][9]. Therefore, air retaining surfaces are of great economic

• and ecological interest for low friction fluid transport and friction reduction on ship hulls [10][11][12]. On some technical superhydrophobic surfaces extremely high drag reduction of up to 50% was measured, but on these surfaces the air film lasted only a short time [13][14][15]. Biological air

Biomimetics inspired surfaces for drag reduction and oleophobicity/philicity

• Bharat Bhushan

Beilstein J. Nanotechnol. 2011, 2, 66–84, doi:10.3762/bjnano.2.9

• a high contact angle and low contact angle hysteresis also exhibit low adhesion and drag reduction for fluid flow. An aquatic animal, such as a shark, is another model from nature for the reduction of drag in fluid flow. The artificial surfaces inspired from the shark skin and lotus leaf have been

• created, and in this article the influence of structure on drag reduction efficiency is reviewed. Biomimetic-inspired oleophobic surfaces can be used to prevent contamination of the underwater parts of ships by biological and organic contaminants, including oil. The article also reviews the wetting

• behavior of oil droplets on various superoleophobic surfaces created in the lab. Keywords: aquatic animals; biomimetics; drag; lotus plants; shark skin; superhydrophobicity; superoleophobicity; Introduction Biologically inspired design, adaptation, or derivation from nature is referred to as ‘biomimetics