Luminescent supramolecular hydrogels from a tripeptide and nitrogen-doped carbon nanodots

• Maria C. Cringoli,
• Slavko Kralj,
• Marina Kurbasic,
• Massimo Urban and
• Silvia Marchesan

Beilstein J. Nanotechnol. 2017, 8, 1553–1562, doi:10.3762/bjnano.8.157

• the applied frequency (see Supporting Information File 1). Overall, from a rheological point of view, the addition of NCNDs increased the peptide hydrogel stability to applied stress and offered the opportunity to fine-tune stiffness or gelation kinetics, depending on the protocol used to prepare the

• applied stress. Importantly, the addition of NCNDs offered the opportunity to fine-tune the gelation kinetics as well as the stiffness of the final material, thus opening new windows of use depending on the intended final application. Interestingly, neither the beta-sheet peptide conformation nor the

3D continuum phonon model for group-IV 2D materials

• Morten Willatzen,
• Lok C. Lew Yan Voon,
• Appala Naidu Gandi and
• Udo Schwingenschlögl

Beilstein J. Nanotechnol. 2017, 8, 1345–1356, doi:10.3762/bjnano.8.136

• : graphene For both graphene and MoS2, the general form of the stiffness tensor for hexagonal structures is and the stress–strain relations TI = cIJSJ for graphene become where TI and SJ denote stress and strain, respectively. Here we have used Voigt notation for tensors. The latter equations are different

• the other group-IV materials even though the following derivation and qualitative properties apply to all of them since they all have the same symmetry of the buckled hexagonal structure, leading to the trigonal D3d point group. The general form of the stiffness tensor for D3d trigonal structures is

• consider the phonons for MoS2 as a prototypical compound 2D material because of its extensively studied properties. As already mentioned, the lack of inversion symmetry leads to the new phenomenon of piezoelectricity. Elastic and electric equations for MoS2 The stiffness tensor for MoS2 is the same as for

Miniemulsion copolymerization of (meth)acrylates in the presence of functionalized multiwalled carbon nanotubes for reinforced coating applications

• Bertha T. Pérez-Martínez,
• Lorena Farías-Cepeda,
• Víctor M. Ovando-Medina,
• José M. Asua,
• Lucero Rosales-Marines and
• Radmila Tomovska

Beilstein J. Nanotechnol. 2017, 8, 1328–1337, doi:10.3762/bjnano.8.134

• in an augmentation of the storage modulus (i.e., stiffness) over the entire temperature range. In addition, the loss modulus of the composites was also higher than that of the blank polymer (Figure 4b), namely the energy dissipation as heat was promoted. This may be due to an additional energy

Assembly of metallic nanoparticle arrays on glass via nanoimprinting and thin-film dewetting

• Sun-Kyu Lee,
• Sori Hwang,
• Yoon-Kee Kim and
• Yong-Jun Oh

Beilstein J. Nanotechnol. 2017, 8, 1049–1055, doi:10.3762/bjnano.8.106

• PDMS were supported on a 1 mm thick glass substrate. The layer thicknesses in the two-layer stamps were determined in order to minimize the distortion of the hard PDMS layer that can occur due to the difference between the stiffness and thermal expansion coefficients of hard PDMS and those of the soft

• , nanoindentation measurements were conducted. The measurements were performed using a nanoindentation system (MTS Nano-indenter XP) equipped with continuous stiffness measurement using a Berkovich indenter, and the elastic modulus and nanohardness were calculated using the method of Oliver and Pharr [32]. The

Bio-inspired micro-to-nanoporous polymers with tunable stiffness

• Julia Syurik,
• Ruth Schwaiger,
• Prerna Sudera,
• Stephan Weyand,
• Siegbert Johnsen,
• Gabriele Wiegand and
• Hendrik Hölscher

Beilstein J. Nanotechnol. 2017, 8, 906–914, doi:10.3762/bjnano.8.92

• potential for impact-resistant components [2] and might also be beneficial to other functional surfaces that, for example, require a stiffness gradient. The recent review by Sahay et al. [5] on synthetic dry adhesives postulates that achieving stiffness gradients is one of the most important goals in

• here for PMMA foams demonstrates a promising method to tailor elastic properties and achieve a stiffness gradient in other thermoplastic polymers without chemical modifications. Such stiffness gradients in thermoplastic polymers can be used in various applications, for example as passive layers for

Functional dependence of resonant harmonics on nanomechanical parameters in dynamic mode atomic force microscopy

• Federico Gramazio,
• Matteo Lorenzoni,
• Francesc Pérez-Murano,
• Enrique Rull Trinidad,
• Urs Staufer and
• Jordi Fraxedas

Beilstein J. Nanotechnol. 2017, 8, 883–891, doi:10.3762/bjnano.8.90

• cantilevers of an atomic force microscope (AFM) as a function of relevant parameters such as the cantilever force constant, tip radius and free oscillation amplitude as well as the stiffness of the sample’s surface. The simulations reveal a universal functional dependence of the amplitude of the 6th harmonic

• experiments confirm the predicted dependence in the explored 3–45 N/m force constant range and 2–345 GPa sample’s stiffness range. For force constants around 25 N/m, the amplitude of the 6th harmonic exhibits the largest sensitivity for ultrasharp tips (tip radius below 10 nm) and polymers (Young’s modulus

• simplified expression is: where kc stands for the cantilever stiffness, z is the distance between the cantilever base and the sample surface and Tn(u) = cos(ncos−1(u)). Note that An decreases for increasing order number (n) and kc values. The tip–surface interaction Fts can be expressed as a function of

Relationships between chemical structure, mechanical properties and materials processing in nanopatterned organosilicate fins

• Gheorghe Stan,
• Richard S. Gates,
• Qichi Hu,
• Kevin Kjoller,
• Craig Prater,
• Kanwal Jit Singh,
• Ebony Mays and
• Sean W. King

Beilstein J. Nanotechnol. 2017, 8, 863–871, doi:10.3762/bjnano.8.88

• the feature size of the organosilicate fins. Specifically, we have observed an inverse correlation between the concentration of terminal organic groups and the stiffness of nanopatterned organosilicate fins. The selective removal of the organic component during etching results in a stiffness increase

• and reinsertion via chemical silylation results in a stiffness decrease. Examination of this effect as a function of fin width indicates that the loss of terminal organic groups and stiffness increase occur primarily at the exposed surfaces of the fins over a length scale of 10–20 nm. While the

• organic component in an organosilicate induced by the plasma etching and ashing processes utilized to transfer lithographically defined features into these materials [32]. Likewise, we have also recently demonstrated the ability of CR-AFM to resolve nanoscale variations in the mechanical stiffness of

Measuring adhesion on rough surfaces using atomic force microscopy with a liquid probe

• Juan V. Escobar,
• Cristina Garza and
• Rolando Castillo

Beilstein J. Nanotechnol. 2017, 8, 813–825, doi:10.3762/bjnano.8.84

• number of contacts between the glass sphere and the peaks for each run. The number of contacts we find in this system ranges between 1 and 5 as shown in Figure 10a. The low number of contacts in this case, the relative insensibility of the pull-off force to the contact length, and the high stiffness of

First examples of organosilica-based ionogels: synthesis and electrochemical behavior

• Andreas Taubert,
• Ruben Löbbicke,
• Barbara Kirchner and
• Fabrice Leroux

Beilstein J. Nanotechnol. 2017, 8, 736–751, doi:10.3762/bjnano.8.77

• stiffness. Although the mechanical properties are still under investigation, the current data show that the organosilica matrix materials exhibit much higher stabilities towards drying and shrinking than conventional silica monoliths. While the latter often break upon drying, the current monoliths do shrink

Optimizing qPlus sensor assemblies for simultaneous scanning tunneling and noncontact atomic force microscopy operation based on finite element method analysis

• Omur E. Dagdeviren and
• Udo D. Schwarz

Beilstein J. Nanotechnol. 2017, 8, 657–666, doi:10.3762/bjnano.8.70

• lateral resolution of the setup. As a consequence, establishing a highly symmetric tunneling connection with the smallest possible stiffness should receive highest priority during the assembly of tuning fork-based sensors. Methods The results presented in the paper expand on a previously introduced

• rises faster than f0 and Δf f0/k, any attempt should be made to keep both k and f0 as low as possible. An increase in the resonance frequency of the sensor can be also an indication of the effective stiffness of the assembly. Finally, the evolution of the perturbation Δy/Δz presents a most unusual

Dispersion of single-wall carbon nanotubes with supramolecular Congo red – properties of the complexes and mechanism of the interaction

• Anna Jagusiak,
• Barbara Piekarska,
• Tomasz Pańczyk,
• Małgorzata Jemioła-Rzemińska,
• Elżbieta Bielańska,
• Barbara Stopa,
• Grzegorz Zemanek,
• Janina Rybarska,
• Irena Roterman and
• Leszek Konieczny

Beilstein J. Nanotechnol. 2017, 8, 636–648, doi:10.3762/bjnano.8.68

• single nanotubes protruding above its surface (Figure 11.2). This can be explained by gel-like properties of the complex formed at high CR/SWNT ratio (see Figure 5B,C), which is a network of nanotubes and supramolecular CR. Elasticity measured as the stiffness range is specified in arbitrary relative

• units. Elasticity reached of about 200 mArb on the free SWNT (black) compared to mica layer (red) (Figure 11.1A). In Figure 11.2A we observed a thick layer of SWNTs covered by CR with elasticity of about 450 mArb, but also bulbs which show much lower stiffness and higher plasticity. These bulbs were

• characteristic: stiffness (elasticity) of the material (DMT Modulus; the higher value of the modified Young's modulus means the more stiff material), adhesion forces (it allows mapping the maximum force with which the microcantilever is attracted by the sample at the time of retract of the piezoelectric scanner

Analysis and modification of defective surface aggregates on PCDTBT:PCBM solar cell blends using combined Kelvin probe, conductive and bimodal atomic force microscopy

• Hanaul Noh,
• Alfredo J. Diaz and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2017, 8, 579–589, doi:10.3762/bjnano.8.62

• correlating the potential and currents in Figure 4 (PPP-CONTSCPt, NanoSensors) has a smaller spring constant (k = 0.5–1.0 N/m) and thus also a weaker torsional stiffness. In general, it is not possible to sustain a repulsive tapping-mode imaging process for the softer cantilever on polymer samples. On the

When the going gets rough – studying the effect of surface roughness on the adhesive abilities of tree frogs

• Niall Crawford,
• Thomas Endlein,
• Jonathan T. Pham,
• Mathis Riehle and
• W. Jon P. Barnes

Beilstein J. Nanotechnol. 2016, 7, 2116–2131, doi:10.3762/bjnano.7.201

• ]. Barnes et al. [19] carried out indentations at different depths and measured different degrees of stiffness at different depths, lower values for the elastic modulus resulting from larger indentations. This is probably due to the stiff outer keratinous surface of the pad. The toes also have extensive

• insufficient fluid to fill the gaps between asperities. Kovalev et al. [39] found a similar result in flies (which have hairy pads), where fluid loss was related to the density of asperities. Attachment is also affected by the pad’s stiffness, a low elastic modulus leading to improved moulding of the pad to

• affected whether the pads made full or only partial contact with the surface. Such a result indicates that the stiffness of the adhesive pad is another critical parameter in adhesion to rough surfaces, whether the pads are smooth or hairy. This analysis enabled the pad’s effective elastic modulus to be

“Sticky invasion” – the physical properties of Plantago lanceolata L. seed mucilage

• Agnieszka Kreitschitz,
• Alexander Kovalev and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2016, 7, 1918–1927, doi:10.3762/bjnano.7.183

• cell wall depend on its chemical composition. For example, the addition of certain matrix substances decreases the cell-wall stiffness [23], and lignification causes a higher mechanical strength [24]. Such changes of mechanical properties can also be seen in the case of mucilaginous cell wall. This

• acetylation [38][39]. The presence of calcium ions slows down water transfer to cellulose and pectins and thus increases the cell-wall stiffness [19][40][41]. Also the presence of boron in the pectic network causes the reduction of the amount of water and contributes the cell-wall strength [19][40]. We can

Noise in NC-AFM measurements with significant tip–sample interaction

• Jannis Lübbe,
• Matthias Temmen,
• Philipp Rahe and
• Michael Reichling

Beilstein J. Nanotechnol. 2016, 7, 1885–1904, doi:10.3762/bjnano.7.181

• : amplitude noise; cantilever stiffness; closed loop; detection system noise; frequency shift noise; non-contact atomic force microscopy (NC-AFM); Q-factor; spectral analysis; thermal noise; tip–sample interaction; Introduction Non-contact atomic force microscopy (NC-AFM) [1][2] is an unmatched surface

• temperature and a quality factor of Q0 = 43900 determined as described elsewhere [14]. The noise floor is determined to and the modal stiffness of the cantilever [20] to k0 = 32.4 N/m from a measurement of the thermally excited cantilever oscillation [11] with the spectrum analyser of the HF2LI device. The

Numerical investigation of depth profiling capabilities of helium and neon ions in ion microscopy

• Patrick Philipp,
• Lukasz Rzeznik and
• Tom Wirtz

Beilstein J. Nanotechnol. 2016, 7, 1749–1760, doi:10.3762/bjnano.7.168

• surface by disordering the surface structure and forming hydrogenated amorphous carbon [4]. Similarly, Ga+ irradiation of polydimethylsiloxane (PDMS) results in micro- and nanopatterns with controlled stiffness for potential applications in tissue engineering [5]. Overall, the properties depend on the

Thickness-modulated tungsten–carbon superconducting nanostructures grown by focused ion beam induced deposition for vortex pinning up to high magnetic fields

• Ismael García Serrano,
• Javier Sesé,
• Isabel Guillamón,
• Hermann Suderow,
• Sebastián Vieira,
• Manuel Ricardo Ibarra and
• José María De Teresa

Beilstein J. Nanotechnol. 2016, 7, 1698–1708, doi:10.3762/bjnano.7.162

• is remarkable that the pinning effect survives at magnetic fields above 2 T. The observation (or lack) of a matching condition is a result of a subtle balance amongst the vortex lattice stiffness, the Lorentz force, the thermal effects, the intrinsic pinning potential and the artificial pinning

Nano- and microstructured materials for in vitro studies of the physiology of vascular cells

• Alexandra M. Greiner,
• Adria Sales,
• Hao Chen,
• Sarah A. Biela,
• Dieter Kaufmann and
• Ralf Kemkemer

Beilstein J. Nanotechnol. 2016, 7, 1620–1641, doi:10.3762/bjnano.7.155

• is required. Additionally, it may be desirable to tune the mechanical stiffness of the material since recent advances in cellular mechanobiology have demonstrated the drastic effect of material compliance on various cell functions [79][80][81][82]. Moreover, the material of choice should also be

• mechanical properties of a substrate. Depending on the tissue in which cells live, the stiffness of the ECM can strongly vary from very low stiffness (e.g., brain: ca. 0.1–3 kPa) to intermediate stiffness (e.g., muscle: ca. 8–17 kPa) to high stiffness (e.g., cartilage: ca. 25–40 kPa) even reaching values in

• produce and their stiffness can be tuned over a wide range (from few tens of pascals to mega- or gigapascals). PEG-DA hydrogels consists of a polymer of ethylene glycol diacrylate monomers [48][161]. By varying the length of the polymer and its ratio with a crosslinker molecule the pore size of the

Biomechanics of selected arborescent and shrubby monocotyledons

• Tom Masselter,
• Tobias Haushahn,
• Samuel Fink and
• Thomas Speck

Beilstein J. Nanotechnol. 2016, 7, 1602–1619, doi:10.3762/bjnano.7.154

• increases and is met by the plants with an increased flexural stiffness via higher axial Young’s moduli. A second important reason might be the advantage of a rather stiff stem for the ability to branch at wide angles, which is typically observed in D. surculosa and D. reflexa. Their wide-angled branchings

• stiffness in young palms that are mechanically “overbuilt” as documented in [8] as they cannot increase their flexural stiffness by secondary growth. This is also supported by the higher stress necessary for rupturing young branches of F. insignis [10], which lacks secondary growth as well. We assume that

• girth and formation of additional vascular bundles, which both contribute to a considerable increase in stiffness: The Young’s moduli in old stages of Dracaena manii of 4.9GP [13] surpass the other values of arborescent young Dracaena species with secondary growth by 5 to 10 times, while they are only

Photothermal effect of gold nanostar patterns inkjet-printed on coated paper substrates with different permeability

• Mykola Borzenkov,
• Anni Määttänen,
• Petri Ihalainen,
• Maddalena Collini,
• Elisa Cabrini,
• Giacomo Dacarro,
• Piersandro Pallavicini and
• Giuseppe Chirico

Beilstein J. Nanotechnol. 2016, 7, 1480–1485, doi:10.3762/bjnano.7.140

• commonly employed material that combines low-cost and excellent environmental compatibility [20]. Furthermore, the physical and chemical properties of this superb printing substrate (e.g., topography, roughness, stiffness, surface energy, polarity, porosity and pore geometry) can be easily tailored by

Fracture behaviors of pre-cracked monolayer molybdenum disulfide: A molecular dynamics study

• Qi-lin Xiong,
• Zhen-huan Li and
• Xiao-geng Tian

Beilstein J. Nanotechnol. 2016, 7, 1411–1420, doi:10.3762/bjnano.7.132

• experiments by using the tip of an atomic force microscope (AFM) and measured the elastic properties of freely suspended multi-layered MoS2 nanosheets (5 to 25 layers). Bertolazzi et al. [10] reported on measurements of the stiffness and breaking strength of monolayer MoS2, found the effective Young's modulus

Functional diversity of resilin in Arthropoda

• Jan Michels,
• Esther Appel and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2016, 7, 1241–1259, doi:10.3762/bjnano.7.115

• molecular prerequisites, resilin features exceptional rubber-like properties including a relatively low stiffness, a rather pronounced long-range deformability and a nearly perfect elastic recovery. Within the exoskeleton structures, resilin commonly forms composites together with other proteins and/or

• polybutadiene [13][14]. Fully hydrated resilin has a rather low stiffness. In the elastic tendons of dragonflies and locust ligaments mentioned above, it was found to have a Young’s modulus of 0.6–0.7 MPa and 0.9 MPa, respectively [11]. In addition, fully hydrated resilin can be stretched to more than three

• within the hard and stiff chitinous structures, which (because of the stiffness of the material) likely requires only small amounts of bending and, therefore, only short muscle contractions [17][18][20]. The flexibility and elasticity of resilin are assumed to facilitate this mechanism by reducing the

Reasons and remedies for the agglomeration of multilayered graphene and carbon nanotubes in polymers

• Rasheed Atif and
• Fawad Inam

Beilstein J. Nanotechnol. 2016, 7, 1174–1196, doi:10.3762/bjnano.7.109

• unstable due to the strain induced by the curvature onto the carbon–carbon bonds. The attraction between the opposing ends of the graphene cylinder surmounts the radial stiffness as the cylinder diameter becomes larger (more than 3 nm) and cylinder tends to flatten [36]. Nanotubes, especially SWNTs, are

Advanced atomic force microscopy techniques III

• Thilo Glatzel and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2016, 7, 1052–1054, doi:10.3762/bjnano.7.98

• Eva Roblegg and co-workers [20]. The local elastic stiffness and damping of individual phases in a titanium alloys was measured by using atomic force acoustic microscopy (AFAM) and mapping of contact-resonance spectra [21]. Another alloy, namely a Pt containing metallic glass, was characterized by AFM

• several transitions in the friction coefficient with increasing load have been found on Au(111) in sulfuric acid electrolyte containing Cu ions by Helmut Baltruschat an co-workers [24] and the stiffness of micron-sized sphere-plate contacts was studied by Diethelm Johannsmann et al. by employing high

Signal enhancement in cantilever magnetometry based on a co-resonantly coupled sensor

• Julia Körner,
• Christopher F. Reiche,
• Thomas Gemming,
• Bernd Büchner,
• Gerald Gerlach and
• Thomas Mühl

Beilstein J. Nanotechnol. 2016, 7, 1033–1043, doi:10.3762/bjnano.7.96

• multiple particles or domains, which then need a more elaborate description. From Equation 3 it is evident that small magnetic samples require a low stiffness as well as a short length of the cantilever which can be achieved by decreasing all of the dimensions of the cantilever as already mentioned above

• paddle-shaped structure positioned somewhere along the length of the cantilever [4][8]. Still, the detection capability limits the decrease in size. Conclusively, there are two competing conditions: on the one hand, the stiffness and length of the cantilever should be very low in order to obtain a strong

• latter with two out of three dimensions on the nanometer scale and therefore with low stiffness and low effective mass. Typical diameters of the iron filling are (15–30) nm and the nanotube length ranges from (15–45) μm [10][11]. The FeCNT not only features favorable geometric and material properties [12