Mapping of elasticity and damping in an α + β titanium alloy through atomic force acoustic microscopy

• M. Kalyan Phani,
• Anish Kumar,
• T. Jayakumar,
• Walter Arnold and
• Konrad Samwer

Beilstein J. Nanotechnol. 2015, 6, 767–776, doi:10.3762/bjnano.6.79

• cantilever model must be taken into account [8], and this has been applied recently to metallic glasses by Wagner et al. [24]. They have successfully demonstrated a quantitative approach to determine the local internal friction or loss at a nanometer scale, using the evaluation procedure of the cantilevers

• different temperatures. In order to effectively obtain the contribution of local internal friction Qloc−1 from the sample, the load of the cantilever onto the sample was chosen to be about 1200 nN for all the measurements. Caron et al. [2] have observed that a background damping in the material related to

• spectra were analyzed using software specifically developed in LabVIEW to obtain the maps of the indentation modulus and damping (i.e., local internal friction). The indentation modulus of the individual phases obtained by AFAM measurements was used to estimate the average modulus of the specimens, using

Entropy effects in the collective dynamic behavior of alkyl monolayers tethered to Si(111)

• Christian Godet

Beilstein J. Nanotechnol. 2015, 6, 583–594, doi:10.3762/bjnano.6.60

• surface chemistry, surface energy, biocompatibility, friction, corrosion, liquid chromatography, interfacial interactions and electronic transport [1][2][3][4][5][6]. More recent studies have been focused on the functionalization of nanostructures. However, in spite of a large number of experimental and

• vibration), is expected to decrease with increasing n-alkyl chain length. Since entropic contributions in the cooperative backbone mobility of tethered molecular layers also appear in the friction dissipation processes (coupling between external shear and internal molecular modes of relaxation) [24], a

Exploiting the hierarchical morphology of single-walled and multi-walled carbon nanotube films for highly hydrophobic coatings

• Francesco De Nicola,
• Paola Castrucci,
• Manuela Scarselli,
• Francesca Nanni,
• Ilaria Cacciotti and
• Maurizio De Crescenzi

Beilstein J. Nanotechnol. 2015, 6, 353–360, doi:10.3762/bjnano.6.34

• ], anti-fouling [47], anti-fogging [48], low-friction coatings [5], adsorption [30], lubrication [22], dispersion [44], and self-assembly [49]. Experimental Fabrication of carbon nanotube films Highly pure SWCNT powder (Sigma-Aldrich, assay >90%, diameter: 0.7–0.9 nm) and MWCNT powder (Nanocyl, NC7000

Aquatic versus terrestrial attachment: Water makes a difference

• Petra Ditsche and
• Adam P. Summers

Beilstein J. Nanotechnol. 2014, 5, 2424–2439, doi:10.3762/bjnano.5.252

• are of higher importance in an aquatic environment. Depending on the flow conditions, flow forces can reach much higher values than gravity and vary in magnitude and direction. For many of the attachment mechanisms (adhesion including glue, friction, suction and mechanical principles such as hook

• pressure difference at vacuum conditions can be ameliorated under water, due to the increasing pressure with water depth. Keywords: adhesion; biofilm; friction; hooks; suction; Introduction Attachment in animals, plants and microorganisms serves a variety of functions: the interconnection of body parts

• , friction drag (or skin friction) and pressure drag (or form drag), which both depend on shape and fluid parameters but in quite different ways [4]. Friction drag is caused by friction of the water flowing over the surface of the animal body. It varies directly with the viscosity of the fluid [4] and the

Modeling viscoelasticity through spring–dashpot models in intermittent-contact atomic force microscopy

• Enrique A. López-Guerra and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 2149–2163, doi:10.3762/bjnano.5.224

• dynamic method and has been the subject of thorough studies [2][3][4][5][6]. In tapping mode AFM damage or wear of the tip and surface are reduced with respect to contact-mode AFM due to lower friction and lateral forces, which makes it more applicable for imaging soft samples, such as polymers and

Nanomanipulation and environmental nanotechnology

• Enrico Gnecco,
• Andre Schirmeisen,
• Carlos M. Pina and
• Udo Becker

Beilstein J. Nanotechnol. 2014, 5, 2079–2080, doi:10.3762/bjnano.5.216

• different substrates. In this way, adhesion and friction can be precisely quantified in different environments. Although very few experiments of this kind have been reported so far, the potential of these techniques is enormous. This Thematic Series is a compilation of papers which provide a wide variety of

• understanding of friction and adhesive forces on the nanoscale. Last but not least, we would like to mention that this Thematic Series was partially inspired by the “Advanced Materials Science Networking (AMASING)” workshop organized by Prof. Gianaurelio Cuniberti in Da Nang, Vietnam, in March 2013. This was

Dissipation signals due to lateral tip oscillations in FM-AFM

• Michael Klocke and
• Dietrich E. Wolf

Beilstein J. Nanotechnol. 2014, 5, 2048–2057, doi:10.3762/bjnano.5.213

• the surface, see Figure 1. In analogy to Equation 1 the effective dynamics for the x-coordinate is given by For the lateral excitations we include a viscous friction term with the coefficient γ, because these losses are not compensated like they are in the bending mode. Commonly, γ is expressed by the

Carbon nano-onions (multi-layer fullerenes): chemistry and applications

• Juergen Bartelmess and
• Silvia Giordani

Beilstein J. Nanotechnol. 2014, 5, 1980–1998, doi:10.3762/bjnano.5.207

• widely studied and have shown promising results as lubricants. In 2002, Cabioc’h et al. reported that CNOs incorporated in silver layers significantly reduced wear, while the friction coefficient is largely unaffected by their presence [74]. Further studies investigated the use of CNOs as a solid state

• ][78][79][80]. Mechanisms by which CNOs can reduce friction and wear were investigated in greater detail in 2009 by Martin and collaborators in a combined experimental and computational study [81]. Computer simulations suggest that the lubrication of CNOs between two surfaces is caused by rolling

Carbon-based smart nanomaterials in biomedicine and neuroengineering

• Antonina M. Monaco and
• Michele Giugliano

Beilstein J. Nanotechnol. 2014, 5, 1849–1863, doi:10.3762/bjnano.5.196

• stimulation and functional scaffolds for tissue engineering). Nanodiamonds (NDs): As a result of the complete sp3 hybridisation of its carbon atoms and its characteristic tetrahedral configuration, diamond shows interesting and peculiar properties such as an extreme hardness, low friction coefficient, high

Mechanical properties of sol–gel derived SiO₂ nanotubes

• Boris Polyakov,
• Mikk Antsov,
• Sergei Vlassov,
• Leonid M Dorogin,
• Mikk Vahtrus,
• Roberts Zabels,
• Sven Lange and
• Rünno Lõhmus

Beilstein J. Nanotechnol. 2014, 5, 1808–1814, doi:10.3762/bjnano.5.191

• study the general flexural behavior of SiO2 NTs. Standard contact AFM cantilevers (ATEC-CONT) were used as the sharp probes. No special procedures were needed for fastening the NTs to the substrate. The static friction between the NT and the substrate was high enough to keep the adhered part of the NT

Equilibrium states and stability of pre-tensioned adhesive tapes

• Carmine Putignano,
• Luciano Afferrante,
• Luigi Mangialardi and
• Giuseppe Carbone

Beilstein J. Nanotechnol. 2014, 5, 1725–1731, doi:10.3762/bjnano.5.182

• theoretical investigations about rough contact mechanics [25][26][27][28][29], the role of roughness in this kind of systems is not yet well understood. Furthermore, viscoelasticity, which entails prominent effects in terms of friction and contact anisotropy [30][31], has not yet been included in analytical

Probing viscoelastic surfaces with bimodal tapping-mode atomic force microscopy: Underlying physics and observables for a standard linear solid model

• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 1649–1663, doi:10.3762/bjnano.5.176

• a ‘friction’ force opposite to its motion, regardless of the direction in which it travels (upward or downward). In contrast, in the SLS model, the dissipation is a consequence of the simple fact that the work done by the cantilever against the surface during the approach is greater than the work

From sticky to slippery: Biological and biologically-inspired adhesion and friction

• Stanislav N. Gorb and
• Kerstin Koch

Beilstein J. Nanotechnol. 2014, 5, 1450–1451, doi:10.3762/bjnano.5.157

• friction are widely-spread in biological systems. They rely on a combination of various mechanisms (Figure 1). Since living creatures move on land, in air and in water, there are numerous mechanical interactions between their body surfaces and the environment. Moreover, the motion of cells and tissues

• inside their bodies is an important part of developmental processes, circulation, respiration, excretion, and any other kind of motility. All these processes rely on adhesion and friction and are continuously under evolutionary pressure, which has contributed to the appearance of highly-specialized

• restricted to selected few model systems most of which deal with materials of the human body or implants. However, a human is only one among millions of living species of organisms, and interesting adhesion- and friction-related contact problems can be found everywhere in biological systems. Different types

Synthesis, characterization, and growth simulations of Cu–Pt bimetallic nanoclusters

• Subarna Khanal,
• Ana Spitale,
• Nabraj Bhattarai,
• Daniel Bahena,
• J. Jesus Velazquez-Salazar,
• Sergio Mejía-Rosales,
• Marcelo M. Mariscal and
• Miguel José-Yacaman

Beilstein J. Nanotechnol. 2014, 5, 1371–1379, doi:10.3762/bjnano.5.150

• with a probe current of 86 pA. Models and simulation method The simulation method employed is a grand-canonical Langevin dynamics (GCLD). Langevin dynamics is a method that extends molecular dynamics to represent the effect of perturbations caused by friction and eventual collisions occurring due to

• stochastic bath. Thus, the solution part contains only metal particles that can either be of the same element as the metal atoms of the nanoparticle or different from them. All solution particles move according to Langevin's equation: where γ is the friction constant, represents the random force acting on

• each particle and represents the force due to the potential interaction between the particles and the NP, as they do not interact with each other. The friction constant γ and the random force are related by the fluctuation–dissipation theorem. The Langevin dynamics was implemented by Ermak's

Surface topography and contact mechanics of dry and wet human skin

• Alexander E. Kovalev,
• Kirstin Dening,
• Bo N. J. Persson and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2014, 5, 1341–1348, doi:10.3762/bjnano.5.147

• skin. The measured friction coefficient between a glass ball and dry and wet skin can be explained assuming that a frictional shear stress σf ≈ 13 MPa and σf ≈ 5 MPa, respectively, act in the area of real contact during sliding. These frictional shear stresses are typical for sliding on surfaces of

• elastic bodies. The big increase in friction, which has been observed for glass sliding on wet skin as the skin dries up, can be explained as result of the increase in the contact area arising from the attraction of capillary bridges. Finally, we demonstrated that the real contact area can be properly

• friction of the wet human skin. However, the pattern of channels on the human skin surface, which is similar to the pattern on channels on the tree frogs toe pads [5], facilitates the fluid removal from the contact regions between skin and countersurface, increases the friction and enhances the grip

Physical principles of fluid-mediated insect attachment - Shouldn’t insects slip?

• Jan-Henning Dirks

Beilstein J. Nanotechnol. 2014, 5, 1160–1166, doi:10.3762/bjnano.5.127

• morphologically different, they both form contact with the substrate via a thin layer of adhesive fluid. To model adhesion and friction forces generated by insect footpads often a simple “wet adhesion” model is used, in which two flat undeformable substrates are separated by a continuous layer of fluid. This

• review summarizes the key physical and tribological principles that determine the adhesion and friction in such a model. Interestingly, such a simple wet-adhesion model falls short in explaining several features of insect adhesion. For example, it cannot predict the observed high static friction forces

• : adhesion; friction; insect biomechanics; tribology; Review How do insects adhere to surfaces? More than 80% of the animal species in the world are arthropods [1], and amongst them insects can be considered probably the evolutionarily most successful group. For hundreds of millions of years they are

Dry friction of microstructured polymer surfaces inspired by snake skin

• Martina J. Baum,
• Lars Heepe,
• Elena Fadeeva and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2014, 5, 1091–1103, doi:10.3762/bjnano.5.122

• influence friction: (1) molecular interaction depending on real contact area and (2) the mechanical interlocking of both contacting surfaces. The strongest reduction of the frictional coefficient, compared to the smooth reference surface, was observed at a medium range of surface structure dimensions

• suggesting a trade-off between these two effects. Keywords: biomimetics; dry friction; microstructure; polymer; snake skin; Introduction Owing to the lack of extremities, the ventral body side of snakes is in almost continuous contact with the substrate. In spite of this, snakes are one of the most

• successful animal groups in occupying niches on all continents, except for Antarctica [1][2][3]. From a tribology point of view, their ventral skin surface has to fulfil two opposite functions: (1) to support body propulsion during locomotion by generating high friction in contact with the substrate and (2

The study of surface wetting, nanobubbles and boundary slip with an applied voltage: A review

• Yunlu Pan,
• Bharat Bhushan and
• Xuezeng Zhao

Beilstein J. Nanotechnol. 2014, 5, 1042–1065, doi:10.3762/bjnano.5.117

• molecules of solid and liquid beside the Lennard-Jones potential, so the boundary slip will be affected by the surface charge. Barrat and Bocquet give a Green–Kubo expression for the interfacial friction coefficient [13]: where μ is the viscosity of the liquid, A = LxLy is the area of the solid surface

A nanometric cushion for enhancing scratch and wear resistance of hard films

• Katya Gotlib-Vainshtein,
• Olga Girshevitz,
• Chaim N. Sukenik,
• David Barlam and
• Sidney R. Cohen

Beilstein J. Nanotechnol. 2014, 5, 1005–1015, doi:10.3762/bjnano.5.114

• Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel 10.3762/bjnano.5.114 Abstract Scratch resistance and friction are core properties which define the tribological characteristics of materials. Attempts to optimize these quantities at solid surfaces are the subject

• is subsequently capped by a titania layer, resulting in enhanced scratch/wear resistance. The physical basis of this effect is explored by means of Finite Element Analysis, and we suggest a model for friction reduction based on the "cushioning effect” of a soft intermediate layer. Keywords: finite

• also give substantial improvement in the wear and friction behavior [2]. A third approach, which has the major advantage of not changing the bulk polymer properties is to use inorganic coatings [9][10]. One such attempt to reduce sensitivity to scratching involves depositing an oxide coating on the

Fibrillar adhesion with no clusterisation: Functional significance of material gradient along adhesive setae of insects

• Stanislav N. Gorb and
• Alexander E. Filippov

Beilstein J. Nanotechnol. 2014, 5, 837–845, doi:10.3762/bjnano.5.95

• segments are marked by black, red and green circles respectively. It is important to mention that our model is certainly limited. It does not account for plastic deformations, geometrical nonlinearity due to large deformations or friction effects. It is focused only on study of the effect of stiffness

Scale effects of nanomechanical properties and deformation behavior of Au nanoparticle and thin film using depth sensing nanoindentation

• Dave Maharaj and
• Bharat Bhushan

Beilstein J. Nanotechnol. 2014, 5, 822–836, doi:10.3762/bjnano.5.94

• grain boundary. The stress at the grain boundary is called the pile up stress, given as where τi is the friction stress opposing the movement of the dislocations. The number of dislocations in the pile up in grain A (n1A) is greater than in grain C (n2C) due to the larger size which leads to a greater

• important for reduced friction and wear. Figure 9 shows examples of load–displacement curves at intermediate and high loads (left) along with topography maps of the nanoparticles over a 10 µm × 10 µm scan area and 2-D profiles before and after indentation (right). The intermediate and high loads were 500

• ). Compression tests, as well as indentation tests, simulate the types of contacts nanoparticles encounter during different friction and wear conditions. For this purpose, a tip approximately 3.5 µm in radius was used to carry out compression tests. Figure 10 shows a typical load displacement curve for

The optimal shape of elastomer mushroom-like fibers for high and robust adhesion

• Burak Aksak,
• Korhan Sahin and
• Metin Sitti

Beilstein J. Nanotechnol. 2014, 5, 630–638, doi:10.3762/bjnano.5.74

• effect of tip apex shape and friction, a model to estimate pull-off stress for mushroom-like fibers, and a comparison between cylindrical and mushroom-like fibers in terms of pull-off stress are discussed. Cohesive zone model Adhesion problems can be studied by using a cohesive zone model such as the

• . Numerical simulations Simulations are performed for a mushroom-like fiber illustrated in Figure 2 by using the analysis software COMSOL MultiPhysics 4.3 FE. It is assumed that the fiber is in full friction contact with a rigid smooth surface, which is in line with our observations during experiments with

• the limit χ → ∞ (i.e., δ → 0) can be explained by using the study of Bogy [43] on stress singularities at bimaterial wedge interfaces. For a soft incompressible elastomer (i.e, Poisson’s ratio ν = 0.5) in full-friction contact with a rigid substrate, stress at the edge of the fiber tip is finite for θ

Manipulation of nanoparticles of different shapes inside a scanning electron microscope

• Boris Polyakov,
• Sergei Vlassov,
• Leonid M. Dorogin,
• Jelena Butikova,
• Mikk Antsov,
• Sven Oras,
• Rünno Lõhmus and
• Ilmar Kink

Beilstein J. Nanotechnol. 2014, 5, 133–140, doi:10.3762/bjnano.5.13

• Nanotechnology Competence Center, Riia 142, 51014, Tartu, Estonia 10.3762/bjnano.5.13 Abstract In this work polyhedron-like gold and sphere-like silver nanoparticles (NPs) were manipulated on an oxidized Si substrate to study the dependence of the static friction and the contact area on the particle geometry

• . Measurements were performed inside a scanning electron microscope (SEM) that was equipped with a high-precision XYZ-nanomanipulator. To register the occurring forces a quartz tuning fork (QTF) with a glued sharp probe was used. Contact areas and static friction forces were calculated by using different models

• and compared with the experimentally measured force. The effect of NP morphology on the nanoscale friction is discussed. Keywords: contact mechanics; nanomanipulation; nanoparticles; nanotribology; scanning electron microscopy (SEM); Introduction The manipulation of nanoparticles (NPs) is a powerful

Friction behavior of a microstructured polymer surface inspired by snake skin

• Martina J. Baum,
• Lars Heepe and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2014, 5, 83–97, doi:10.3762/bjnano.5.8

• of the biological model, Lampropeltis getula californiae, the California King Snake, on the friction behavior. For this purpose, we compared snake-inspired anisotropic microstructured surfaces to other microstructured surfaces with isotropic and anisotropic geometry. To exclude that the friction

• measurements were influenced by physico-chemical variations, all friction measurements were performed on the same epoxy polymer. For frictional measurements a microtribometer was used. Original data were processed by fast Fourier transformation (FFT) with a zero frequency related to the average friction and

• adaptation to reduce wear. Based on this extensive comparative study of different microstructured polymer samples, it was experimentally demonstrated that the friction-induced stick-slip behavior does not solely depend on the frictional coefficient of the contact pair. Keywords: fast Fourier transformation

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

• manipulation, i.e., the collision between the probing tip and the particle, the friction between the particles and the substrate, the role of water when measuring in ambient (lubrication, capillary effects, etc.), electrostatics between them, etc. The high surface to volume ratio of nanoparticles makes them

• adhesion strength of calcium fluoride nanoparticles adsorbed on mica and on tooth enamel in liquid with AM-AFM. Theory As already described above, manipulation experiments in the tapping-mode are difficult to quantify as dynamic and friction processes are involved at the same time. To connect the power