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

• 0.3–1.3 eV) and log(fB0) (in the range from 1010 to 1024 Hz). The latter apparent prefactor values exceed typical phonon frequencies (1013 Hz) by more than ten decades. This "compensation law" observed for solid-state phenomena with a large activation energy in many areas (physics, mechanics

• point" temperature TF should decrease with increasing n-alkane length. OML mechanics: compressive and shear forces In this section, the molecular layer is considered as a continuous medium submitted to a compressive electrostatic pressure, proportional to VI2, where VI is the potential drop across the

Dynamic force microscopy simulator (dForce): A tool for planning and understanding tapping and bimodal AFM experiments

• Horacio V. Guzman,
• Pablo D. Garcia and
• Ricardo Garcia

Beilstein J. Nanotechnol. 2015, 6, 369–379, doi:10.3762/bjnano.6.36

• instantaneous deflection and tip–surface force, velocity, virial, dissipated energy, sample deformation and peak force as a function of time or distance. The simulator includes a variety of interactions and contact mechanics models to describe AFM experiments including: van der Waals, Hertz, DMT, JKR, bottom

• tip–surface charge density and σs is the sample surface charge density. Hertz contact mechanics The elastic contact between the tip and sample is usually modelled with the Hertz model [46] whereby for a spherical tip and a half-space sample the force is given by where δ is the indentation and Eeff is

• the effective Young modulus of the interface defined by where Et and Es are the Young’s modulus of the tip and sample, respectively, and υt and υs are the Poisson coefficients of the tip and sample, respectively. Derjaguin–Mueller–Toporov contact mechanics (DMT) The DMT model is valid for describing

The effect of surface charge on nonspecific uptake and cytotoxicity of CdSe/ZnS core/shell quantum dots

• Vladimir V. Breus,
• Anna Pietuch,
• Marco Tarantola,
• Thomas Basché and
• Andreas Janshoff

Beilstein J. Nanotechnol. 2015, 6, 281–292, doi:10.3762/bjnano.6.26

• ). Thus, even though the MTS assay indicated that the cells were still healthy and retained their initial level of vitality within 24 h of exposure to QDs, the particles affected the dynamics and mechanics of MDCKII cell division and changed the properties of the plasma membrane. In Figure 2a, impedance

Mechanical properties of MDCK II cells exposed to gold nanorods

• Anna Pietuch,
• Bastian Rouven Brückner,
• David Schneider,
• Marco Tarantola,
• Christina Rosman,
• Carsten Sönnichsen and
• Andreas Janshoff

Beilstein J. Nanotechnol. 2015, 6, 223–231, doi:10.3762/bjnano.6.21

• of cells mirror the environment such as substrate properties including topography and stiffness [16][17][18]. Besides, also chemical cues can produce substantial changes in membrane or cytoskeletal mechanics and dynamics providing an excellent means to assess the impact of external stimuli such as

• the elasticity of the epithelial cell line MDCK II probed by AFM and QCM. The combination of these two techniques allows to monitor the influence of nanoparticles on the elastic properties of MDCK II cells both from the apical and basal side. The data permits to compare mechanics of cells exposed to

• nanoparticles impact cell mechanics. Results and Discussion Figure 1 shows microscopy (AFM and fluorescence microscopy) images of a confluent MDCK II monolayer treated with CTAB-coated gold nanorods. CTAB is necessary to keep the particles in solution preventing precipitation due to aggregation. The AFM images

Multifunctional layered magnetic composites

• Maria Siglreitmeier,
• Baohu Wu,
• Tina Kollmann,
• Martin Neubauer,
• Gergely Nagy,
• Dietmar Schwahn,
• Vitaliy Pipich,
• Damien Faivre,
• Dirk Zahn,
• Andreas Fery and
• Helmut Cölfen

Beilstein J. Nanotechnol. 2015, 6, 134–148, doi:10.3762/bjnano.6.13

• ][55] and films [56][57][58][59]. However, due to the morphological and structural inhomogeneity of our samples it is currently difficult to make a quantitative evaluation of the data. Continuum mechanics models typically require homogeneous and isotropic materials. For pure gelatin we can successfully

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

• be a monolayer of water on the surface of the leaf, or there might be a patch of standing water on the leaf after rainfall. Even in this terrestrial example, there is the possibility of submerged mechanics applying at some size scale. Similarly, there are cases in the fully submerged environment

• where terrestrial mechanics might apply. For example, when spiders bring with them a ball of air as they dive beneath the surface, or when two superhydrophobic surfaces interact underwater. Therefore, the first task that we face is to make clear what we mean as we try to distinguish between these two

Nanometer-resolved mechanical properties around GaN crystal surface steps

• Jörg Buchwald,
• Marina Sarmanova,
• Bernd Rauschenbach and
• Stefan G. Mayr

Beilstein J. Nanotechnol. 2014, 5, 2164–2170, doi:10.3762/bjnano.5.225

• paper can be generalized, due to the fact that they are based on a general formalism introducing surface stresses in continuum mechanics and since many other materials ranging from ionic crystals [11] to metals [12] are known to form such steps. Theoretical considerations A step can be described by 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

• contact mechanics to incorporate the contact area and sample deformation [7]. The dissipative part of this model, originally introduced by García and coworkers [34] has the following form: where η is the viscosity, R is the tip radius and δ is the sample deformation (tip–sample indentation). In this model

• SLS is the simplest model that is able to describe stress relaxation and creep, and the DMT is a widely used model in contact mechanics that is typically used in the context of AFM. We include both DMT contact forces and long-range van der Waals forces [6][32]. where H is the Hammaker constant, R is

Modification of a single-molecule AFM probe with highly defined surface functionality

• Fei Long,
• Bin Cao,
• Ashok Khanal,
• Shiyue Fang and
• Reza Shahbazian-Yassar

Beilstein J. Nanotechnol. 2014, 5, 2122–2128, doi:10.3762/bjnano.5.221

• Fei Long Bin Cao Ashok Khanal Shiyue Fang Reza Shahbazian-Yassar Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan, USA Department of Chemistry, Michigan Technological University, 1400 Townsend Drive, Houghton

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

• processes. For example, the photocatalytic degradation of pollutants can be interpreted using density functional theory. On a different scale, AFM measurements in liquid environments can be supported by advanced contact mechanics models including the squeeze-out of wetting fluids. Adhesion of fluorite

Patterning a hydrogen-bonded molecular monolayer with a hand-controlled scanning probe microscope

• Matthew F. B. Green,
• Taner Esat,
• Christian Wagner,
• Philipp Leinen,
• Alexander Grötsch,
• F. Stefan Tautz and
• Ruslan Temirov

Beilstein J. Nanotechnol. 2014, 5, 1926–1932, doi:10.3762/bjnano.5.203

• adsorption mechanics of PTCDA on Ag(111) is well understood: a PTCDA molecule binds to the metal surface through an extended bond that involves charge transfer into its LUMO and also locally with its four carboxylic oxygen atoms [10][11] (marked by white circles in Figure 1a). The same atoms enable SPM

Spin annihilations of and spin sifters for transverse electric and transverse magnetic waves in co- and counter-rotations

• Hyoung-In Lee and
• Jinsik Mok

Beilstein J. Nanotechnol. 2014, 5, 1887–1898, doi:10.3762/bjnano.5.199

• ] but also to the vector potential leading to the Landau levels in quantum mechanics [19]. Let us refer again to the schematic Figure 1a in both Cartesian and cylindrical coordinates, where a cylinder located at r = R divides the interior from exterior. Figure 1b displays the TE and TM waves, each being

• the kinetic momentum in the Hamiltonian, in which the light-matter interactions lead to the quantized Landau levels in quantum mechanics [19]. See Section S7 of Supporting Information File 1 for details. As with , in the interior for the counter-rotational case, as seen from the vanishing denominator

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

• indentation is limited to the thin-shell or membrane case [27]. Therefore, for the case of thick shells studied in this work, we employed finite element method (FEM, COMSOL Multiphysics) models instead, where all geometric parameters can be taken into account. The Solid Mechanics module was used, where the

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

Hydrophobic interaction governs unspecific adhesion of staphylococci: a single cell force spectroscopy study

• Nicolas Thewes,
• Peter Loskill,
• Philipp Jung,
• Henrik Peisker,
• Markus Bischoff,
• Mathias Herrmann and
• Karin Jacobs

Beilstein J. Nanotechnol. 2014, 5, 1501–1512, doi:10.3762/bjnano.5.163

• bacterium/surface contact. Since the exact contact formation and mechanics between the bacterial surface and the solid substrate is unclear, it is hard to make predictions on the shape of the force/distance curve. Upon retraction, the force/distance curve exhibits first the same steep slope as upon approach

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

• theoretical studies which range from insect adhesion, bacterial adhesion and skin friction to artificial biomimetic systems, e.g., snake-skin inspired polymer patterns or gecko tape. The Thematic Series does not attempt to give a comprehensive overview of the emerging field of biological contact mechanics

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

• topography of the human wrist skin is studied by using optical and atomic force microscopy (AFM) methods. By using these techniques the surface roughness power spectrum is obtained. The Persson contact mechanics theory is used to calculate the contact area for different magnifications, for the dry and wet

• defined only when a combination of both AFM and optical methods is used for power spectrum calculation. Keywords: contact mechanics; interface fluid; roughness power spectrum; skin tribology; Introduction The tribology of human skin is of great importance in sports, medicine, and cosmetics [1][2]. It is

• ]. In a first approximation, a two layers model, with a thin stiff layer on top of a thick soft layer, is sufficient for a satisfactory description of the contact mechanics between the skin and the indentor. The change of skin morphology and elastic modulus in the wet state contributes to the high

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

• increases the capillary force. This extended capillary model might add an explanation why some insects (and tree frogs) have soft toe pads [51]. It should also be noted that in particular in the context of insect adhesion the mechanics described by the third viscous forces, or “Stefan adhesion” term, are a

Trade-offs in sensitivity and sampling depth in bimodal atomic force microscopy and comparison to the trimodal case

• Babak Eslami,
• Daniel Ebeling and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 1144–1151, doi:10.3762/bjnano.5.125

• , feature sizes, shapes and patterns, which have been previously attributed by others to the competing effects of membrane functionality and contact mechanics on the cantilever response [19]. In cases in which the mechanics of the subsurface are of interest, it is necessary to operate the AFM in a way that

Molecular biology approaches in bioadhesion research

• Marcelo Rodrigues,
• Birgit Lengerer,
• Thomas Ostermann and
• Peter Ladurner

Beilstein J. Nanotechnol. 2014, 5, 983–993, doi:10.3762/bjnano.5.112

• techniques that are of particular interest to researchers working on bioadhesion of organisms where no reference genome exists. Important prerequisites of bioadhesion research are based on techniques such as histology, biochemistry and mechanics [1][3] but gradually certain model systems are entering

Growth and characterization of CNT–TiO₂ heterostructures

• Yucheng Zhang,
• Ivo Utke,
• Johann Michler,
• Gabriele Ilari,
• Marta D. Rossell and
• Rolf Erni

Beilstein J. Nanotechnol. 2014, 5, 946–955, doi:10.3762/bjnano.5.108

• Yucheng Zhang Ivo Utke Johann Michler Gabriele Ilari Marta D. Rossell Rolf Erni Electron Microscopy Center, EMPA, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland Laboratory of Mechanics of Materials and Nanostructure, EMPA, Swiss

Direct observation of microcavitation in underwater adhesion of mushroom-shaped adhesive microstructure

• Lars Heepe,
• Alexander E. Kovalev and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2014, 5, 903–909, doi:10.3762/bjnano.5.103

• in predominantly liquid environments. Keywords: bio-inspired; biomimetic; cavitation; contact mechanics; gecko; interface; negative pressure; pull-off; surface; tribology; Introduction During the past two decades, bio-inspired microstructured adhesives became a new class of adhesive materials with

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

• gradients of material properties in real beetle setae was used in the numerical model presented below. Numerical model In principle, to model mechanics of the setae a classical beam theory can be applied. However, for long array of the beams it needs in extremely time consuming numerical calculation. To

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

• 'Biodiversity in change' of the Academy of Sciences and Literature in Mainz. The authors thank the Botanical Gardens of the University Bonn for the cultivation and kind provision of the Salvinia plants. We acknowledge our partners, the working group of Professor Alfred Leder (Chair of Fluid Mechanics - LSM) at

The softening of human bladder cancer cells happens at an early stage of the malignancy process

• Jorge R. Ramos,
• Joanna Pabijan,
• Ricardo Garcia and
• Malgorzata Lekka

Beilstein J. Nanotechnol. 2014, 5, 447–457, doi:10.3762/bjnano.5.52

• cell and the extracellular matrix, and the presence or development of progressive diseases. However, the specific role of the mechanical properties of the cells and the extracellular matrix in pathogenesis such as tumor progression remain poorly understood at best. The relationship between mechanics at

• the cellular level and tumorigenesis represents a new perspective for which many issues need to be addressed. The studies of cell mechanics have gained great importance with the advent of AFM measurements, which demonstrated the capability to probe single cells and underlining a correlation between

• cell mechanics, in particular elasticity, and cancer [5][6]. The first measurements showed that cancerous human bladder cells were softer than non-malignant bladder cells. Further measurements of cancerous cells have confirmed that a lowering of the elastic modulus of the cells is a general feature of