Electronic and electrochemical doping of graphene by surface adsorbates

• Hugo Pinto and
• Alexander Markevich

Beilstein J. Nanotechnol. 2014, 5, 1842–1848, doi:10.3762/bjnano.5.195

• until equilibrium is reached, Eredox = EF, making graphene n- (p-)type doped. In contrast to electronic doping, which occurs instantaneously, electrochemical doping is a time-dependent process, which is affected by the rate of the reaction and diffusion rates of participating species. Therefore, in the

Biocompatibility of cerium dioxide and silicon dioxide nanoparticles with endothelial cells

• Claudia Strobel,
• Martin Förster and
• Ingrid Hilger

Beilstein J. Nanotechnol. 2014, 5, 1795–1807, doi:10.3762/bjnano.5.190

• -inflammatory effects, a slight pro-thrombotic impact, and an increase of reactive oxygen species after nanoparticle exposure were observed with increasing incubation time. For SiO2 nanoparticles, concentration- and time-dependent effects on the metabolic activity as well as pro-inflammatory reactions were

• (dimethylethyl)phenyl)-N’-(3-(triethoxysilyl)propyl)perylene-3,4,9,10-tetracarboxylic acid diimide label); magnification: 20×. CeO2 nanoparticles revealed concentration- and time-dependent effects on the cellular adenosine triphosphate (ATP) level. Immortalized human microvascular endothelial cells (HMEC-1) and

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

• behavior of the probe–sample forces, although significant progress has already been achieved by using multi-frequency methods [9]. The contact models used so far are not true viscoelastic models, since they do not exhibit time-dependent stress and strain relaxation, but they have been shown to be

• solution of the cantilever equations of motion in the form of boundary conditions at the tip [4][5]. This model can reproduce time-dependent creep compliance (time-dependent strain relaxation under a constant stress) with high accuracy, but not stress relaxation (time dependent drop in stress under a

• dissipated during successive tip–sample impacts (this dissipation was calculated by integrating numerically the area of the dissipation loops), and panel (c) shows a few examples of successive tip–sample impacts, illustrated as time-dependent forces. Interestingly, even in the case in which the peak

Multi-frequency tapping-mode atomic force microscopy beyond three eigenmodes in ambient air

• Santiago D. Solares,
• Sangmin An and
• Christian J. Long

Beilstein J. Nanotechnol. 2014, 5, 1637–1648, doi:10.3762/bjnano.5.175

• time-dependent trajectory of the tip and individual eigenmodes through simulation of ideal cantilevers. Figure 2a illustrates typical tip trajectories simulated for pentamodal operation when imaging a polymer sample. Here the first eigenmode free amplitude is 80 nm and the higher mode free amplitudes

• carried out and the apparent robustness of our results, the non-uniformity of successive tip–sample impacts, the nonlinear coupling of the various eigenmodes, as well as time-dependent tip–sample behaviors such as viscoelasticity suggest that unless single-cycle techniques [16][18][30] can be implemented

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

• . The number of intracellular particles varied considerably from cell to cell. About 30 cells were evaluated per time point, thus resulting in more than 360 cells in total. The statistics for the number of taken up particles per HUVEC or HeLa cells are plotted in Figure 3. A time-dependent increase of

• plays an important role in our findings. Cell division is probably among the dominant causes for the observed dilution of nanoparticles. Yet, other time-dependent parameters may also influence the uptake dynamics. For example, degradation of intracellular particles, exocytosis, cell uptake behavior (e.g

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

• the order of a fraction of a second) does not influence the adhesion force. The snap-in separation, however, decreases with increasing tip velocity (Figure 5B), as does the snap-in force (Figure 5C), which is a first indication to a time-dependent contact-process, which will be detailed in the

The cell-type specific uptake of polymer-coated or micelle-embedded QDs and SPIOs does not provoke an acute pro-inflammatory response in the liver

• Markus Heine,
• Alexander Bartelt,
• Oliver T. Bruns,
• Denise Bargheer,
• Artur Giemsa,
• Barbara Freund,
• Ludger Scheja,
• Christian Waurisch,
• Alexander Eychmüller,
• Rudolph Reimer,
• Horst Weller,
• Peter Nielsen and
• Joerg Heeren

Beilstein J. Nanotechnol. 2014, 5, 1432–1440, doi:10.3762/bjnano.5.155

• organs to the kidneys was observed. These findings are supported by a study in rats describing a time-dependent increase in the cadmium concentration over 30 days after injection of QDs in the kidneys indicating that these nanocrystals are slowly degraded in vivo [11]. In summary, despite the breakdown

• metals such as cadmium released from QDs or iron released from SPIOs did not acutely influence the inflammatory status of the liver. However, specific target cells can be of transient relevance and heavy metals released after QDs or SPIOs uptake may traverse through different target cell types in a time

• -dependent manner. Given the limitation of the study that gene expression of pro-inflammatory markers was analysed 48 h (Figure 3) or 4 h (Figure 6) after the injection of nanoparticles, we cannot exclude that different target cells in different organs such as the kidney, spleen, adipose tissues or the bone

The protein corona protects against size- and dose-dependent toxicity of amorphous silica nanoparticles

• Dominic Docter,
• Christoph Bantz,
• Dana Westmeier,
• Hajo J. Galla,
• Qiangbin Wang,
• James C. Kirkpatrick,
• Peter Nielsen,
• Michael Maskos and
• Roland H. Stauber

Beilstein J. Nanotechnol. 2014, 5, 1380–1392, doi:10.3762/bjnano.5.151

• . Comprehensive experimental approaches, such as quantifying cellular metabolic activity, microscopic observation of cell morphology, and high-throughput cell analysis revealed a dose- and time-dependent toxicity primarily upon exposure with ASP30 (Ø = 30 nm). Albeit smaller (ASP20, Ø = 20 nm) or larger particles

• the Caco-2 cells following exposure to the different ASP (Figure 2). Exposure to ASP30 or ASP30L under serum free conditions induced dose- and time-dependent significant morphological changes, such as loss of a structured cell shape, disruption of the monolayer, and loss of adhesion, which is

• cellular enzymes that reduce the tetrazolium dye MTT to its insoluble formazan in living cells. Compared to untreated control cells, exposure to ASP30 was found to significantly reduce the cell vitality in a dose- and time-dependent manner (Figure 3A), whereas no effects were observed upon treatment with

Mimicking exposures to acute and lifetime concentrations of inhaled silver nanoparticles by two different in vitro approaches

• Fabian Herzog,
• Kateryna Loza,
• Sandor Balog,
• Martin J. D. Clift,
• Matthias Epple,
• Peter Gehr,
• Alke Petri-Fink and
• Barbara Rothen-Rutishauser

Beilstein J. Nanotechnol. 2014, 5, 1357–1370, doi:10.3762/bjnano.5.149

• . As a release of cytokines could not be detected with ELISA we assume that this is a transient and acute effect, which decreases to normal levels within a short time. Dependent on how NPs are applied, i.e., either by submerged or ALI conditions, different toxicological results can be obtained [60

Electron-beam induced deposition and autocatalytic decomposition of Co(CO)₃NO

• Florian Vollnhals,
• Martin Drost,
• Fan Tu,
• Esther Carrasco,
• Andreas Späth,
• Rainer H. Fink,
• Hans-Peter Steinrück and
• Hubertus Marbach

Beilstein J. Nanotechnol. 2014, 5, 1175–1185, doi:10.3762/bjnano.5.129

• , which points to a deposition that is influenced by proximity effects [2]. In addition to the dose dependence, the growth time-dependent appearance of the structures was investigated. Figure 3 compares SEM images of square deposits fabricated by EBID and autocatalytic growth, using Co(CO)3NO as precursor

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

• account the viscosity of the mediating fluid layer. Two parallel smooth surfaces with a distance of h sliding at a velocity v relative to each other generate the friction force where ηeff is the effective viscosity of the mediating fluid layer and A the size of the contact area. Again, similar to the time

• -dependent viscous adhesion (Equation 2), the v/h-term in Equation 5 shows that a simple fluid mediated system at rest should not be able to generate any static friction. Based on viscosity estimations from dewetting processes (40 to 150 mPa), Federle et al. showed that the hydrodynamic friction forces

DFT study of binding and electron transfer from colorless aromatic pollutants to a TiO₂ nanocluster: Application to photocatalytic degradation under visible light irradiation

• Corneliu I. Oprea,
• Petre Panait and
• Mihai A. Gîrţu

Beilstein J. Nanotechnol. 2014, 5, 1016–1030, doi:10.3762/bjnano.5.115

• ]. Building upon the experience gained while modeling materials for photoelectrochemical cells, we report here results of DFT and time dependent DFT (TD-DFT) calculations performed on several colorless aromatic pollutants, as well as complex systems consisting of benzene derivatives adsorbed on a TiO2

• of vibrational analyses. Time-dependent DFT [37] calculations of the molecular orbitals and the electronic transitions were performed in water by means of the polarizable continuum model (PCM) [38][39]. We used the same B3LYP functional and TZVP basis sets [36]. In the case of the pollutants adsorbed

Double layer effects in a model of proton discharge on charged electrodes

• Johannes Wiebe and
• Eckhard Spohr

Beilstein J. Nanotechnol. 2014, 5, 973–982, doi:10.3762/bjnano.5.111

• charge on the metal slab. Far from the electrode only the two charged states can contribute to the EVB ground state so that the state of a proton is a time-dependent superposition state of two different H3O+ states. The proton complex thus dynamically moves between more hydronium and more Zundel like

• developed by Warshel to study proton transfer mechanisms in biological systems [19][20][21]. This methodology was later extended by various groups to study proton dynamics in water [22][23] in a chemically intuitive picture, in which the proton state is described as (to a first approximation) a time

• -dependent superposition of Eigen, H9O4+, and Zundel, H5O2+, cations. Multistate generalizations of this simple picture were later applied to a variety of physical, chemical and biological problems [24][25][26][27][28]. In order to utilize the methodology for highly acidic environments such as a fuel cell

Designing magnetic superlattices that are composed of single domain nanomagnets

• Derek M. Forrester,
• Feodor V. Kusmartsev and
• Endre Kovács

Beilstein J. Nanotechnol. 2014, 5, 956–963, doi:10.3762/bjnano.5.109

• the x and y components, is applied with frequency fapplied = fγMs and amplitude Ha = Msha. The angle of deviation between the applied field and the x-axis of the superlattice is β, and λ is a small time-dependent perturbation in hy with amplitude 0.02 (the perturbation has its origin in a thermally

Controlling mechanical properties of bio-inspired hydrogels by modulating nano-scale, inter-polymeric junctions

• Seonki Hong,
• Hyukjin Lee and
• Haeshin Lee

Beilstein J. Nanotechnol. 2014, 5, 887–894, doi:10.3762/bjnano.5.101

• and height of 1 mm. The time dependent rheology test showed that the sol–gel transition was finished within 1 min (data not shown). In order to test the mechanical properties of the hydrogels in a stable condition, we carried out the frequency and strain sweep test 10 min after the gel formed

Classical molecular dynamics investigations of biphenyl-based carbon nanomembranes

• Andreas Mrugalla and
• Jürgen Schnack

Beilstein J. Nanotechnol. 2014, 5, 865–871, doi:10.3762/bjnano.5.98

• first step towards a deeper understanding of the structure and formation of carbon nanomembranes. Future investigations will focus on the dynamical aspects of the membrane formation. For such simulations thermostatted classical molecular dynamics [29][30][31][32][33], with possibly time-dependent

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

• . Stiff, medium and soft segments are marked by black, red and green circles respectively. The subplots in the bottom (from left to right) show time dependent vertical force, evolution of the array of distances dxj = xj+1 − xj between contact ends of nearest neighbors and instant histogram P(dx) of the

• , because flexible filaments are too long in the case (b). Last case (c) with long hard filaments rotating around their flexible roots, cannot perfectly adapt to the surface. As a result, maximum of the attachment force here remains much lower than in two previous cases (a) and (b). To accumulate time

• -dependent information about deformations of the fibers we calculate array {dxj}, j = 1,2,…Nx of the distances between contact ends of the nearest neighbors dxj = xj+1 − xj. Let us note that we are using dxj for small but finite distances (not differential). We use this notation to conserve coincidence with

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

• understanding of materials behavior during contact. Mechanical properties of interest comprise hardness, Young’s modulus of elasticity, bulk modulus, elastic–plastic deformation, scratch resistance, residual stresses, time-dependent creep and relaxation properties, fracture toughness, fatigue and yield strength

Antimicrobial properties of CuO nanorods and multi-armed nanoparticles against B. anthracis vegetative cells and endospores

• Pratibha Pandey,
• Merwyn S. Packiyaraj,
• Himangini Nigam,
• Gauri S. Agarwal,
• Beer Singh and
• Manoj K. Patra

Beilstein J. Nanotechnol. 2014, 5, 789–800, doi:10.3762/bjnano.5.91

• (qualigens) consists of spheroidal micrometer-scaled particles up to 100 µm size having rough surfaces [16]. Antibacterial test against B. anthracis vegetative cells The time dependent antibacterial efficacy of CuO nanorods (PS2) against B. anthracis bacterial cells and E. coli cells at a dose of 1 mg/mL is

• very limited penetration and accumulation inside the cell [22]. The dose- and time-dependent bactericidal activity of multi-armed CuO nanoparticles (P5) against 7.0 × 105 CFU/mL B. anthracis vegetative cells at dose range of 0.5 to 6 mg/mL is shown in Figure 4. The graph also compares bactericidal

• -synthesized precursor of PS2. d) EDX spectrum of PS2. Time dependent bactericidal activity of CuO nanorods (PS2) at a dose of 1 mg/mL against B. anthracis vegetative cells and E. coli cells in saline media. Time dependent bactericidal activity of CuO multi-armed NPs (P5) at doses of 0.5 and 2 mg/mL against B

Artificial sunlight and ultraviolet light induced photo-epoxidation of propylene over V-Ti/MCM-41 photocatalyst

• Van-Huy Nguyen,
• Shawn D. Lin,
• Jeffrey Chi-Sheng Wu and
• Hsunling Bai

Beilstein J. Nanotechnol. 2014, 5, 566–576, doi:10.3762/bjnano.5.67

• experiments using only UV light. Figure 6 shows the time-dependent behavior of the photocatalytic reaction when using artificial sunlight. With respect to time on stream, the PO formation rate increased to a peak value of 151 µmol·gcat−1·h−1 after 1 h and then it decayed to 81 µmol·gcat−1·h−1 after 24 h

• illumination. Figure 8 shows the time-dependent behavior of the photocatalytic reaction when using different filters with UV light. The PO selectivity was stable even under UV-C range of 250–400 nm. On the whole, an increase in light intensity promoted the activity and resulted in increased C3H6 consumption

Control theory for scanning probe microscopy revisited

• Julian Stirling

Beilstein J. Nanotechnol. 2014, 5, 337–345, doi:10.3762/bjnano.5.38

• linearity of the feedback response. We shall refer to this log tunnel current as where is the time dependent operator fully describing the tunnel junction, the I–V amplifier, and the logarithm operation. The feedback controller then compares I(t) with a set-point, P, and tries to correct for discrepancies

• by modifying the output, O(t), to the z-piezo. We can write the feedback controller as the time-dependent operator , and hence Finally, we can link the z-piezo extension to the feedback controller output with an operator, . This describes both the high voltage amplifier use for the piezoelectric

Frequency, amplitude, and phase measurements in contact resonance atomic force microscopies

• Gheorghe Stan and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 278–288, doi:10.3762/bjnano.5.30

• band excitation (BE) method, a time-dependent signal containing a band of frequencies around the desired resonance is applied at each pixel of the scan, such that the frequency response at that location can be rapidly obtained through a Fourier transform of the cantilever tip response and a fit to a

Constant-distance mode SECM as a tool to visualize local electrocatalytic activity of oxygen reduction catalysts

• Michaela Nebel,
• Thomas Erichsen and
• Wolfgang Schuhmann

Beilstein J. Nanotechnol. 2014, 5, 141–151, doi:10.3762/bjnano.5.14

• pulse profile and the time of data acquisition [29]. Due to this complex multiparameter system, the experimental conditions for the best data acquisition varies for each measurement. By means of the 4D SF/CD-RC-SECM a technique is accessible that enables a time-dependent data acquisition at various

• closest approach. To additionally implement the redox competition mode, a variable potential pulse profile is performed at each tip-to-sample distance. During a competition pulse tip and sample compete for the oxygen inside the gap and a time-dependent current decay curve is recorded at the tip enabling a

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

• known to be time-dependent [4]. The initial displacement was followed by a controlled manipulation of the particle by pushing it with the tip while simultaneously recording the force in the scan regime (a detailed description of SmarAct manipulator regimes is given in Supporting Information File 1

In situ growth optimization in focused electron-beam induced deposition

• Paul M. Weirich,
• Marcel Winhold,
• Christian H. Schwalb and
• Michael Huth

Beilstein J. Nanotechnol. 2013, 4, 919–926, doi:10.3762/bjnano.4.103

• mutation method. The parents of the new parameter sets are chosen via an uniform distributed random choice. The crossover method is performed by exchanging parameters of the parents. For the mutation method parameters are chosen randomly within the given parameter-range. A representative time-dependent

• -time and pitch as obtained from the GA experiments, the resistivity of W–C–O samples can be tuned by one order of magnitude. Time-dependent rate of change of conductance for Pt–C deposits - The GA is applied for the optimization of conductance during post-irradiation with electrons (U = 5 kV, Inominal