Model systems for studying cell adhesion and biomimetic actin networks

• Dorothea Brüggemann,
• Johannes P. Frohnmayer and
• Joachim P. Spatz

Beilstein J. Nanotechnol. 2014, 5, 1193–1202, doi:10.3762/bjnano.5.131

• regulation of morphological changes in such synthetic cells was explained by a balance of actomyosin cortical tension and mechanical resistance to rupture [71]. For the functional encapsulation of cytoskeletal proteins into lipid vesicles high physiological salt levels are mandatory and the fabrication

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

• , undeformable disk and substrate with a mediating continuous fluid-layer (see Figure 2 and [30][38][39][40][41][42]). In this simple model, the total adhesive force is basically the sum of three components: the surface tension of the fluid, the Laplace pressure (both often combined as “capillary forces”) and

• mediating fluid volume should decline over time. In a static adhesive pad with a Newtonian fluid, only the (negligible) surface tension and the small Laplace pressure would thus determine the overall adhesive force of the insect foot (Table 1). Fluid-mediated friction forces In a fluid mediated system with

• a continuous Newtonian fluid film, the friction forces between the substrates can in general be described by using two basic principles: the surface tension of the mediating fluid and the laws of hydrodynamic lubrication [55][56]. Surface tension The contribution of the surface tension of the

Nanoforging – Innovation in three-dimensional processing and shaping of nanoscaled structures

• Andreas Landefeld and
• Joachim Rösler

Beilstein J. Nanotechnol. 2014, 5, 1066–1070, doi:10.3762/bjnano.5.118

• also limited by the surface tension of the cast-material. Some complex three dimensional shapes were realized by casting of metal with a low melting temperature [3][4]. Dimensions of cast details are in the submillimeter- and microscale, and due to the mentioned limitations, applications in the

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

• section, a summary and an outlook are provided. Review 1 Contact angle and contact angle hysteresis with applied voltage When a voltage is applied to a droplet deposited on a solid surface, the surface tension between solid and liquid changes, which leads to a change of the wettability of the surface, the

• so called electrowetting [10][11][64][65]. The surface tension between solid and liquid decreases with increasing applied voltage, leading to a decrease of the CA. The change of the CA with the applied voltage V can be expressed by the Young–Lippmann equation [64][66] as: where θ0 is the original CA

• in the absence of an voltage, C is the capacitance of the dielectric layer, and γlv is the surface tension between liquid and vapor. In 1875, Lippmann found the electrowetting phenomenon and presented the Young–Lippmann equation, which is acknowledged as the basic of the electrowetting theory. In

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

• negative pressure (tension), the pull-off forces were consistently lower, around 50%, of those measured under ambient conditions. This result supports the assumption that the recently observed strong underwater adhesion of MSAMS is due to an air layer between individual MSAMSs [Kizilkan, E.; Heepe, L

• hypothesized that the enhanced underwater adhesion may be a result of cavitation under each individual MSAMS when entrapped water in the contact area is subjected to a negative pressure (tension) during pull-off and the liquid water turns into vapor at a certain cavitation threshold [19]. This effect would

• a dry contact underwater, (2) MSAMS and glass are separated by (thin) water layer. Instead we observed that water inclusions present at the interface are subjected to negative pressure (tension) during applied pull-off. However, for individual MSAMSs used in this work, we did not observe higher

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

• increasing far field displacement causes a cohesive zone to form at the edge first. Since δc is relatively large for low χ, increase in tension does not immediately result in a crack to initiate at the edge. In the meantime the stress in the center gradually increases reaching σo at which a second cohesive

Hairy suckers: the surface microstructure and its possible functional significance in the Octopus vulgaris sucker

• Francesca Tramacere,
• Esther Appel,
• Barbara Mazzolai and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2014, 5, 561–565, doi:10.3762/bjnano.5.66

• Figure 1g), responsible for the detachment of the acetabular protuberance from the upper surface of the side wall of the orifice, needs to be balanced. In [5], such a force is balanced by the cohesive forces of the water in the infundibular portion (the water under tension behaves like a solid) (please

Calibration of quartz tuning fork spring constants for non-contact atomic force microscopy: direct mechanical measurements and simulations

• Jens Falter,
• Marvin Stiefermann,
• Gernot Langewisch,
• Philipp Schurig,
• Hendrik Hölscher,
• Harald Fuchs and
• André Schirmeisen

Beilstein J. Nanotechnol. 2014, 5, 507–516, doi:10.3762/bjnano.5.59

• , Fachbereich Bauingenieurwesen) for the tension-test of the “Torr Seal” samples as well as Werner David and Stephan Diekmann (“Feinmechanische Werkstatt”, Physikalisches Institut, WWU Münster) for support and fruitful discussion. Financial support by the Deutsche Forschungsgemeinschaft (DFG) through the

Nanoscale particles in technological processes of beneficiation

• Sergey I. Popel,
• Vitaly V. Adushkin and
• Anatoly P. Golub'

Beilstein J. Nanotechnol. 2014, 5, 458–465, doi:10.3762/bjnano.5.53

• side of the vapor, and η and σ are the viscosity and surface tension of the liquid, respectively. The set of equations of gas-dynamics, which is solved together with the van der Waals equation of state describes the vapor motion as well as the pressure, the temperature, and the internal energy inside

Tensile properties of a boron/nitrogen-doped carbon nanotube–graphene hybrid structure

• Kang Xia,
• Haifei Zhan,
• Ye Wei and
• Yuantong Gu

Beilstein J. Nanotechnol. 2014, 5, 329–336, doi:10.3762/bjnano.5.37

• materials. Keywords: doping; graphene; molecular dynamics simulation; nanotubes; tension; Young’s modulus; Introduction In recent years, low-dimensional structures such as carbon nanotubes (CNT) and graphene have attracted huge attention of the scientific community, because of their excellent performance

• and graphene sheets are connected. After the bonds begin to break, the hybrid structure quickly fails. This phenomenon is indicated by the sharp decrease of the stress (Figure 2a), which indicates a brittle behavior. Such brittle behavior can be easily explained as the tension loading direction is

Fabrication of carbon nanomembranes by helium ion beam lithography

• Xianghui Zhang,
• Henning Vieker,
• André Beyer and
• Armin Gölzhäuser

Beilstein J. Nanotechnol. 2014, 5, 188–194, doi:10.3762/bjnano.5.20

• approximately 200 µC/cm2 and approximately 480 µC/cm2, respectively. A possible explanation for this behaviour can be found by considering the in-plane tension of cross-linked SAMs. It is known that free-standing CNMs from fully cross-linked NBPT SAMs exhibit an in-plane tensile residual strain of about 1% [4

Size-dependent characteristics of electrostatically actuated fluid-conveying carbon nanotubes based on modified couple stress theory

• Mir Masoud Seyyed Fakhrabadi,
• Abbas Rastgoo and
• Mohammad Taghi Ahmadian

Beilstein J. Nanotechnol. 2013, 4, 771–780, doi:10.3762/bjnano.4.88

• static pull-in voltage is decreased because of a lowered stiffness. This can be attributed to the axial force that is induced by the fluid flow. For the cantilevered CNT, the axial force is tension because the free end does not apply any external force on the system. However, for the doubly clamped

Large-scale atomistic and quantum-mechanical simulations of a Nafion membrane: Morphology, proton solvation and charge transport

• Pavel V. Komarov,
• Pavel G. Khalatur and
• Alexei R. Khokhlov

Beilstein J. Nanotechnol. 2013, 4, 567–587, doi:10.3762/bjnano.4.65

• incompatible H and P units can form thin channels and slits permeating through a matrix of a majority hydrophobic component [76]. The origin of such morphologies has been discussed for these materials and the physical forces responsible are well recognized. Essentially interfacial tension controls their

• morphologies. The interfacial tension tends to decrease interfacial stretching, thereby leading to the formation of highly curved monolayers consisting of amphiphilic units with their polar groups in contact with water and hydrophobic groups shielded from contacting the water. When the concentration of these

Ni nanocrystals on HOPG(0001): A scanning tunnelling microscope study

• Michael Marz,
• Keisuke Sagisaka and
• Daisuke Fujita

Beilstein J. Nanotechnol. 2013, 4, 406–417, doi:10.3762/bjnano.4.48

• theory [27]), i.e., in the limit of small deformations. Thus, the adhesive force can be written as where γx is the surface tension and R the radius of the cluster, assuming a spherical particle. With γHOPG = 1.75 J/m2, γNi = 2.45 J/m2, and R = 5.9 nm, a pull off force of Fa = −4.36 nN is expected. The

High-resolution nanomechanical analysis of suspended electrospun silk fibers with the torsional harmonic atomic force microscope

• Mark Cronin-Golomb and
• Ozgur Sahin

Beilstein J. Nanotechnol. 2013, 4, 243–248, doi:10.3762/bjnano.4.25

• the influence of tension and bending modulus on the response of the suspended structures. Here we report mechanical measurements on electrospun silk fibers with various treatments that allow discriminating among the different mechanisms that determine the mechanical behavior of these complex

• structures. In particular we were able to identify the role of tension and boundary conditions (pinned versus clamped) in determining the mechanical response of electrospun silk fibers. Our findings show that high-resolution mechanical imaging with torsional harmonic atomic force microscopy provides a

• example, the use of local interaction models provides limited information in the case of suspended structures where bending modulus, geometry, and mechanical tension are the key determinants of tip–sample interactions. The interpretation of measurements on these kinds of samples requires simultaneous

Electrospinning preparation and electrical and biological properties of ferrocene/poly(vinylpyrrolidone) composite nanofibers

• Ji-Hong Chai and
• Qing-Sheng Wu

Beilstein J. Nanotechnol. 2013, 4, 189–197, doi:10.3762/bjnano.4.19

• morphologies of the fibers. It is considered that the viscosity and surface tension of the solution changes with increasing Fc content, which leads to this result [30][31]. The characterization of typical samples obtained was summarized in Table 1. In the experiment we found that when the amount of the Fc was

Hydrogen-plasma-induced magnetocrystalline anisotropy ordering in self-assembled magnetic nanoparticle monolayers

• Alexander Weddemann,
• Judith Meyer,
• Anna Regtmeier,
• Irina Janzen,
• Dieter Akemeier and
• Andreas Hütten

Beilstein J. Nanotechnol. 2013, 4, 164–172, doi:10.3762/bjnano.4.16

• equilibrium states. The experimental results will be compared to numerical calculations based on the idea that the plasma induces a process comparable to the time-dependent creep under tension in which the plasma acts as thermal activation. Experimental Measurements were carried out with two different species

• comparable to mechanical creep under tension with the hydrogen plasma acting as the thermal actuator. With the stray-field energy minimum obtained for an in-plane magnetic configuration, the easy magnetocrystalline axes of individual particles should migrate into the particle plane, resembling the respective

• with the stray field of contiguous nanocrystals. The process is comparable to the time-dependent creep under tension with the plasma acting as the thermal activation. For uniaxial magnetocrystalline anisotropy, the migration of the magnetocrystalline easy axes results in an increase of the effective

Size-dependent phase diagrams of metallic alloys: A Monte Carlo simulation study on order–disorder transitions in Pt–Rh nanoparticles

• Johan Pohl,
• Christian Stahl and
• Karsten Albe

Beilstein J. Nanotechnol. 2012, 3, 1–11, doi:10.3762/bjnano.3.1

• surface in the microcanonical ensemble can be a useful theoretical tool, because convex intruders of the entropy can be used as a concept to assign first-order transitions even in finite systems, and additional quantities, such as the interface tension between phases, become accessible [9]. A quantitative

Direct monitoring of opto-mechanical switching of self-assembled monolayer films containing the azobenzene group

• Einat Tirosh,
• Enrico Benassi,
• Silvio Pipolo,
• Marcel Mayor,
• Michal Valášek,
• Veronica Frydman,
• Stefano Corni and
• Sidney R. Cohen

Beilstein J. Nanotechnol. 2011, 2, 834–844, doi:10.3762/bjnano.2.93

• molecular-level mechanical manipulators. As an example, macroscopic transport at the solid–liquid interface was driven by modifying the solid–liquid surface tension at a droplet front by using a molecular switch based on a SAM of rotaxane [8]. Central to the function of such systems are changes in the inter

Mechanical characterization of carbon nanomembranes from self-assembled monolayers

• Xianghui Zhang,
• André Beyer and
• Armin Gölzhäuser

Beilstein J. Nanotechnol. 2011, 2, 826–833, doi:10.3762/bjnano.2.92

• [10]. In this system, the tension of the CNM is assumed to be the main contribution balancing the AFM tip force. The force contributed by the bending stiffness and the adhesion between the tip and the membrane was neglected. For a pressurized membrane, the indentation depth δ decreases with increasing

Surface induced self-organization of comb-like macromolecules

• Konstantin I. Popov,
• Vladimir V. Palyulin,
• Martin Möller,
• Alexei R. Khokhlov and
• Igor I. Potemkin

Beilstein J. Nanotechnol. 2011, 2, 569–584, doi:10.3762/bjnano.2.61

• . The free energy was calculated by summation of the bending energy of the wormlike chain of the backbone, the Maier–Saupe contribution for LC ordering of side LC chains, the stretching energy of the amorphous block, the surface tension and the mixing Flory–Huggins contributions. Later studies [95][96

• of two different cylindrical and four different types of lamellar phases were found (Figure 3). Conditions for stability of each structure can be summarized as follows [96]: Amorphous cylinders: Long macromolecules; high fraction of the B and C (LC) units; any values of the surface tension

• coefficients satisfying the strong segregation conditions. Liquid crystalline cylinders: Long macromolecules; high fraction of the A units and small enough fraction of the liquid crystalline units; any values of the surface tension coefficients satisfying the strong segregation conditions. AB lamellae: Long

Simulation of bonding effects in HRTEM images of light element materials

• Simon Kurasch,
• Jannik C. Meyer,
• Daniela Künzel,
• Axel Groß and
• Ute Kaiser

Beilstein J. Nanotechnol. 2011, 2, 394–404, doi:10.3762/bjnano.2.45

• low spatial frequencies resulting in enhanced contrast of the substitution defects. The other parameters were: High tension 80 kV and spherical aberration Cs = 0.02 mm. Higher order aberrations were not taken into account in this study. The resulting micrographs for the boron substitution are shown in

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

• understood [17]. The Hildebrand solubility parameter, expressed as a square root of cohesive energy density, can also be correlated with the surface tension (γL) [32], e.g., by the Equation 1 (where VL is molar volume of a liquid) [33][34]: However, a critical parameter for the flow of a liquid through

• 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

• (penetration depth, radius of the channel) and variable parameters (surface tension and contact angle) (Equation 4): were H is the final height of the liquid in the capillary. The values of the surface tension for all infiltrating liquids are all within the same order of magnitude. The values of contact angle

Moisture harvesting and water transport through specialized micro-structures on the integument of lizards

• Philipp Comanns,
• Christian Effertz,
• Florian Hischen,
• Konrad Staudt,
• Wolfgang Böhme and
• Werner Baumgartner

Beilstein J. Nanotechnol. 2011, 2, 204–214, doi:10.3762/bjnano.2.24

• pressure, i.e., the atmospheric pressure plus the hydrostatic pressure acting on the liquid. γ is the surface tension, φ is the contact angle of the liquid on the unstructured capillary material, r is the radius of the capillary, η is the viscosity of the liquid, and ε is the coefficient of slip. The

Infrared receptors in pyrophilous (“fire loving”) insects as model for new un-cooled infrared sensors

• David Klocke,
• Anke Schmitz,
• Helmut Soltner,
• Herbert Bousack and
• Helmut Schmitz

Beilstein J. Nanotechnol. 2011, 2, 186–197, doi:10.3762/bjnano.2.22

• on the temperature profile, the equation of state must be solved. Because the pressure in the cavity depends upon two independent variables, temperature and volume, its total change is given by with ΔP: Pressure increase, β = (∂P/∂T)V: isochoric tension coefficient, ΔTmean: mean temperature increase

• be calculated as a function of the factor Ω by using Equation 2 and Equation 4. with α = β·κ: isobaric thermal expansion coefficient. Equation 4 and Equation 5 can be also used for a gas-filled cavity. In this case the isochoric tension coefficient β and the isothermal compression coefficient κ can

• be calculated from the ideal gas law with n: number of moles of gas in the cavity, R: universal gas constant. Equation 6 yields the following expression for the isochoric tension coefficient β, the isothermal compression coefficient κ and the isobaric thermal expansion coefficient α If the change of