Nanostructuring of GeTiO amorphous films by pulsed laser irradiation

• Valentin S. Teodorescu,
• Cornel Ghica,
• Adrian V. Maraloiu,
• Mihai Vlaicu,
• Andrei Kuncser,
• Magdalena L. Ciurea,
• Ionel Stavarache,
• Ana M. Lepadatu,
• Nicu D. Scarisoreanu,
• Andreea Andrei,
• Valentin Ion and
• Maria Dinescu

Beilstein J. Nanotechnol. 2015, 6, 893–900, doi:10.3762/bjnano.6.92

• for plastic flow. Such a mechanism can be imagined based on the shear transformation-zone theory of plastic deformation near the glass transition [30]. The temperature due to the laser heating was estimated by using the Heat Flow software [24]. Figure 8 shows the temperature variation at different

Stiffness of sphere–plate contacts at MHz frequencies: dependence on normal load, oscillation amplitude, and ambient medium

• Jana Vlachová,
• Rebekka König and
• Diethelm Johannsmann

Beilstein J. Nanotechnol. 2015, 6, 845–856, doi:10.3762/bjnano.6.87

• can be explained by nanoroughness. In other words, contact splitting (i.e., a transport of shear stress across many small contacts, rather than a few large ones) can be exploited to reduce partial slip. Keywords: contact mechanics; contact splitting; contact stiffness; partial slip; quartz crystal

• be tested easily. The experiments were undertaken with a quartz crystal microbalance (QCM). The QCM is mostly known as a device for thickness determination, but it can equally well be employed to measure contact stiffness. In this regard, it is helpful to view the QCM as a shear wave reflectometer

• related to the dissipation factor, D, by D = Γ/(2f). fF is the fundamental frequency, which is often 5 MHz. Zq = 8.8 × 106 kg∙m−2s−1 is the shear wave impedance of AT-cut quartz. is the area-averaged complex amplitude of the tangential stress at the resonator surface, and u0 is the amplitude of

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

• dissipation mechanisms is the behavior of tethered OML under compressive and shear forces, as found in nano-tribology experiments, where external forces can cause conformational changes. Again, a disorder gradient results from the formation of gauche defects which can be reverted when the atomic force

• excitations collected from a thermal bath. c) The applied bias dependence of activation energies is tentatively related to compression and shear stresses expected for an OML considered as a continuous medium submitted to a compressive force (Figure 1) [49]. Finally, on the basis of the bias dependence of the

• 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

Influence of grain size and composition, topology and excess free volume on the deformation behavior of Cu–Zr nanoglasses

• Daniel Şopu and
• Karsten Albe

Beilstein J. Nanotechnol. 2015, 6, 537–545, doi:10.3762/bjnano.6.56

• from a homogeneous to an inhomogeneous plastic deformation, because the softer interfaces are promoting the formation shear transformation zones. In case of the Cu-rich system, shear localization at the interfaces is most pronounced, since both the topological order and free volume content of the

• interfaces don’t show topological disorder. Our results provide clear evidence that the mechanical properties of metallic NGs can be systematically tuned by controlling the size and the chemical composition of the glassy nanograins. Keywords: enhanced plasticity; metallic glasses; nanoglasses; shear bands

• annihilation spectroscopy [9], while molecular dynamics studies showed that glass–glass interfaces exhibit an excess free volume and a modified local order [10][11]. If plastically deformed, the soft glass in the interfaces promotes shear band nucleation similar to the effect of residual shear bands in pre

Filling of carbon nanotubes and nanofibres

• Reece D. Gately and
• Marc in het Panhuis

Beilstein J. Nanotechnol. 2015, 6, 508–516, doi:10.3762/bjnano.6.53

• removal of the encapsulated nanoparticles [95]. Sonication has also been employed to fill MWCNTs in solution. Sonication acted to shear the MWCNT, resulting in the filling of the MWCNT with the surrounding metal solution [96]. Other methods have employed focused electron irradiation to produce SWCNTs

A scanning probe microscope for magnetoresistive cantilevers utilizing a nested scanner design for large-area scans

• Tobias Meier,
• Alexander Förste,
• Ali Tavassolizadeh,
• Karsten Rott,
• Dirk Meyners,
• Roland Gröger,
• Günter Reiss,
• Eckhard Quandt,
• Thomas Schimmel and
• Hendrik Hölscher

Beilstein J. Nanotechnol. 2015, 6, 451–461, doi:10.3762/bjnano.6.46

• while holding the large-area scanner at a fixed position. The high resolution open-loop scanner is thereby mounted on a large-area scan stage. The high resolution scanner was realized by using a stack of shear actors for x–y scanning and a stack piezo actor with a travel of 5 μm and a resonance

A surface acoustic wave-driven micropump for particle uptake investigation under physiological flow conditions in very small volumes

• Florian G. Strobl,
• Dominik Breyer,
• Phillip Link,
• Adriano A. Torrano,
• Christoph Bräuchle,
• Matthias F. Schneider and
• Achim Wixforth

Beilstein J. Nanotechnol. 2015, 6, 414–419, doi:10.3762/bjnano.6.41

• uptake of nanoparticles. Here, we present a versatile microfluidic device based on acoustic streaming induced by surface acoustic waves (SAWs). The device offers a convenient method for introducing fluid motion in standard cell culture chambers and for mimicking capillary blood flow. We show that shear

• physiological flow conditions the particle uptake rates for this system are significantly lower than at low shear conditions. This underlines the vital importance of the fluidic environment for cellular uptake mechanisms. Keywords: acoustic streaming; cellular uptake; flow; nanoparticles; sedimentation; shear

• Cloc > Cm. Ignoring these effects can in fact lead to misinterpretation of experimental data, especially to an overestimation of the impact of big particles or agglomerates. Furthermore, particles on a cell surface under shear are subject to drag and torsion forces [3]. For spherical particles in the

The fate of a designed protein corona on nanoparticles in vitro and in vivo

• Denise Bargheer,
• Julius Nielsen,
• Gabriella Gébel,
• Markus Heine,
• Sunhild C. Salmen,
• Roland Stauber,
• Horst Weller,
• Joerg Heeren and
• Peter Nielsen

Beilstein J. Nanotechnol. 2015, 6, 36–46, doi:10.3762/bjnano.6.5

• of particles <10 nm is more and more balanced by shear forces due to Brownian motion with the consequence of detachment of proteins. The authors explained their finding with a heteroaggregation model in which a low number of SPIOs is stabilized between layers of proteins. In our FPLC study we do not

Intake of silica nanoparticles by giant lipid vesicles: influence of particle size and thermodynamic membrane state

• Florian G. Strobl,
• Florian Seitz,
• Christoph Westerhausen,
• Armin Reller,
• Adriano A. Torrano,
• Christoph Bräuchle,
• Achim Wixforth and
• Matthias F. Schneider

Beilstein J. Nanotechnol. 2014, 5, 2468–2478, doi:10.3762/bjnano.5.256

• and the release of cargo from giant vesicles was also the subject of earlier works in our group [35][36]. Due to the non-zero lateral shear resistance of gel-phase membranes, the relaxation time for the healing of defects will be much longer as compared to liquid membranes. Hence, induced pores remain

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

• surfaces. Additional capillary bridges between foot and substrate are formed due to the fluid secreted by the beetle and shear adhesion forces are in the same range as in air [43]. Similar results were described for geckos attaching to hydrophilic surfaces underwater and in air while no significant

• actually the force needed to shear the junctions formed between the surfaces in contact. In contrast, in wet friction a film of water or another liquid is involved. This liquid can originate from humidity in the air or from secretion by the animal. Under such boundary lubrication conditions there is a

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

• in-plane bending of half-suspended NT. In all experiments the tip oscillated parallel to the surface of the sample (shear mode) and normal to the NTs. The amplitude signal of the QTF (proportional to the applied force) and the sequence of SEM images of the gradually bent NT were recorded

Non-covalent and reversible functionalization of carbon nanotubes

• Antonello Di Crescenzo,
• Valeria Ettorre and
• Antonella Fontana

Beilstein J. Nanotechnol. 2014, 5, 1675–1690, doi:10.3762/bjnano.5.178

• provided by magnetic stirring, reflux, shear mixing, or, most commonly, ultrasonication either mild sonication in a bath or high-power sonication using a tip [16]. Once exfoliated, the simplest stable CNTs dispersions have been achieved by using solvent molecules able to efficiently interact with CNTs such

Precise quantification of silica and ceria nanoparticle uptake revealed by 3D fluorescence microscopy

• Adriano A. Torrano and
• Christoph Bräuchle

Beilstein J. Nanotechnol. 2014, 5, 1616–1624, doi:10.3762/bjnano.5.173

• nanoparticles. The flow is generated by a novel microfluidic reactor that can be combined with live-cell imaging and is able to cover the entire physiological range of shear rates [31]. Comparison to other methods Customary techniques performed for achieving the dosage of particles taken up by cells include

On the structure of grain/interphase boundaries and interfaces

• K. Anantha Padmanabhan and
• Herbert Gleiter

Beilstein J. Nanotechnol. 2014, 5, 1603–1615, doi:10.3762/bjnano.5.172

• about two and a half atomic diameters (average grain boundary width [58]) in the perpendicular direction. (A deformation of oblate spheroids of such dimensions along the interface between glassy regions in case of metallic glasses would lead to the formation of shear transformation zones, described by

• Argon [59] and others.) As mentioned above, the basic units of boundary/interface sliding are defined around free volume sites, which are present at discrete places characteristic of the interatomic forces and the boundary misorientation. The sequential shear of such oblate spheroids, when it reaches

• summarized in [53][54][55][56][57][60][61][62]. The shear modulus and the free volume present in the basic sliding unit, γ0, (composition, impurity/solute/dopant content dependent) can be determined by using ab initio calculations, in particular the tight binding model, which is computationally less

Silica nanoparticles are less toxic to human lung cells when deposited at the air–liquid interface compared to conventional submerged exposure

• Alicja Panas,
• Andreas Comouth,
• Harald Saathoff,
• Thomas Leisner,
• Marco Al-Rawi,
• Michael Simon,
• Gunnar Seemann,
• Olaf Dössel,
• Sonja Mülhopt,
• Hanns-Rudolf Paur,
• Susanne Fritsch-Decker,
• Carsten Weiss and
• Silvia Diabaté

Beilstein J. Nanotechnol. 2014, 5, 1590–1602, doi:10.3762/bjnano.5.171

• , the importance of shear forces to exacerbate NP-induced toxicity has been described previously [8][33]. Another explanation could also be the secretion of surfactant by A549 cells under ALI conditions [34] which may have a protective effect due to binding of surfactant proteins to the particles [35

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

• type shown in Figure 6 it is given by , where and [14][15][16] where where G0 = E0/2(1+ν0) and G1 = E1/2(1+ν1) are the shear moduli for solid 0 and solid 1, respectively. In all the calculations presented below we have assumed a squeezing pressure FN/A0 = p0 = 6.83 kPa, which is the average nominal

• /A0 = σN/σY = 1.37 × 10−4. Plastic deformation starts at q ≥ 105 m−1 corresponding to a wavelength of λ ≤ 2π/q ≈ 60 μm. The values of the friction coefficients, μ ≈ 0.25 for dry skin and μ ≈ 1.4 for wet skin, could be explained by frictional shear stresses of about 13 MPa for the dry surface and of

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

• mm2 [16], the maximal possible shear stress before sliding occurs (with cos α1 − cos α2 ≤ 2) would be only approx. 0.38 kPa. This value (and the corresponding value for smaller contact areas) is several orders of magnitude smaller than the shear stresses measured in smooth adhesive pads of the stick

• generated by a continuous fluid film of 90 nm height would be one order of magnitude smaller than the shear stresses observed in adhesive organs [30]. Thus it is not yet clear how insects with a fluid-mediated adhesive pad generate the observed friction forces preventing them from sliding down smooth

• results suggest that thixotropic (shear-thinning) non-Newtonian properties of the secretion could explain the presence of high static friction forces [46][60]. A second, yet to be tested, hypothesis to explain the observed high friction forces is the formation of local “dry” rubber like direct contacts

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

• images of the tip used for the experiments. The simulation was executed by MSC.MARC FE code, and used a bilinear shear, Coulomb model for the friction. Contact conditions are defined only between the indenter tip and the TiO2 layer. During the simulation, the indenter is first pressed against the layer

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

• -shaped contact geometry (see review [4]), which have been studied intensively under various loads (e.g., preload [5][6], shear [7][8], overload [9], and tilt [10][11]) and environmental conditions (e.g., dry in air [5][6][7][8][9][10][11][12], oil lubricated [13], on rough substrates [13][14][15], in

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

• multiple contacts that contribute to an enhancement of overall length of the total peeling line [7]. We have recently shown that thin tape-like contact tips of hairs (setae) in combination with applied shear force lead to the formation of maximal real contact area without slippage within the contact [8

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

• dependent on the indenter shape, the shear modulus and H0. The ISE contributes to increased hardness in bulk solid surfaces, thin films and nano-objects. Hall–Petch effect The generation of dislocations leads to the Hall–Petch effect through the dislocation pile up mechanism or the dislocation density

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

• these results are important for designing dry fibrillar adhesives, they are only concerned with the performance when the loading is axial. The effect of shear loading should also be considered along with the results of this study in designing fibrillar adhesives. Scanning electron microscope image of

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

• adhesion conditions, a system consisting of hairs, mucus, and water (just like octopus suckers) could improve attachment due to following mechanisms: (i) exploiting the presence of mucus and filaments to increase the viscosity coefficient at the interface and to resist to the shear forces; and (ii

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

• beam length values, a deviation can be noticed. The contribution caused by the torsion can be calculated analytically by the following relation [21]: in which T is the torsional momentum, Φt is the angle of twist in radians, L the length at which the force is applied, G the shear momentum and IT the

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

• voltage were 20–50 mV and the corresponding tip oscillation amplitude was in order of 100 nm. The tip oscillated parallel to the sample surface, i.e., in the shear mode [20]. The QTF force sensors were calibrated on a reference contact mode AFM cantilever (NT-MDT, CSG11), which was previously calibrated

• S5, Supporting Information File 1) the NP often moved aside affected by the tip oscillation (Figure 5). Moreover, the force necessary to displace a NP can be overestimated due to an unaccounted amount of energy dissipated in a shear interaction between the tip and the NP. For the parallel tip

• calculated the friction force values, Ffriction, by using a simple relation: where τ is the interfacial shear stress/strength and A is the contact area [26]. The shear strength is defined as an ultimate shear stress τ before the object is displaced, and can be estimated by using the relation τtheo = G*/Z