Atomic-level characterization and cilostazol affinity of poly(lactic acid) nanoparticles conjugated with differentially charged hydrophilic molecules

• María Francisca Matus,
• Martín Ludueña,
• Cristian Vilos,
• Iván Palomo and
• Marcelo M. Mariscal

Beilstein J. Nanotechnol. 2018, 9, 1328–1338, doi:10.3762/bjnano.9.126

• , Langevin dynamics were performed on these final structures with a friction coefficient of 30 ps−1. In this way, the solvent particles are omitted, and their effects are represented by a combination of random forces and frictional terms. Simulations of 1 ns were carried out. The velocity Verlet-like

Atomistic modeling of tribological properties of Pd and Al nanoparticles on a graphene surface

• Alexei Khomenko,
• Miroslav Zakharov,
• Denis Boyko and
• Bo N. J. Persson

Beilstein J. Nanotechnol. 2018, 9, 1239–1246, doi:10.3762/bjnano.9.115

• insight into the fundamental origin of sliding friction. Results: Using molecular dynamics we investigate frictional properties of aluminum and palladium nanoparticles deposited on a graphene layer. We study the time evolution of the total momentum of the system, the total and potential energies, the

• temperature, the velocity and position of the center of mass, the dimensions of the nanoparticle, and the friction and substrate forces acting on the particle. We also study how the friction force depends on the nanoparticle–graphene contact area and the temperature. Conclusion: The tribological properties of

• nanoparticles strongly depend on the materials. The particles move in an irregular (saw-like) manner. The averaged friction force depends nearly linearly on the contact area and non-monotonously on temperature. We observe ordered crystalline domains of atoms at the bottom surface of the metal particles, but the

Surface characterization of nanoparticles using near-field light scattering

• Eunsoo Yoo,
• Yizhong Liu,
• Chukwuazam A. Nwasike,
• Sebastian R. Freeman,
• Brian C. DiPaolo,
• Bernardo Cordovez and
• Amber L. Doiron

Beilstein J. Nanotechnol. 2018, 9, 1228–1238, doi:10.3762/bjnano.9.114

• and waveguide surface is represented by a friction force, Ffric, which is a complex function of numerous dynamic properties. We use a simple approach, assuming Ffric is inversely proportional to height and increases linearly with velocity (Ffric = Av/z, where A is a constant and v is the velocity). By

Scanning speed phenomenon in contact-resonance atomic force microscopy

• Christopher C. Glover,
• Jason P. Killgore and
• Ryan C. Tung

Beilstein J. Nanotechnol. 2018, 9, 945–952, doi:10.3762/bjnano.9.87

• . [13] predicted the theoretical scanning speed limit, in terms of the maximum achievable resolution, and other researchers such as Bosse et al. [14] have created methods to more accurately measure relevant system parameters, such as the friction coefficient, at higher scan speeds. What is not fully

• has an effect on the friction [18][19]. Furthermore, this effect depends on the scan speed and can bring the system from a stick–slip state to a “steady sliding” state above a critical velocity [18]. It is noted that “a small viscous damping contribution in the tip–sample contact is sufficient enough

Effect of microtrichia on the interlocking mechanism in the Asian ladybeetle, Harmonia axyridis (Coleoptera: Coccinellidae)

• Jiyu Sun,
• Chao Liu,
• Bharat Bhushan,
• Wei Wu and
• Jin Tong

Beilstein J. Nanotechnol. 2018, 9, 812–823, doi:10.3762/bjnano.9.75

• a cyclical change from sparse to dense in each segment in the middle of the abdomen. Furthermore, the different directions of microtrichia that lead to self-locking friction on the surfaces of the hindwing, elytron and abdomen appear to facilitate interlocking. A model for the interlocking of the

• include producing stridulations through interactions with the elytra, thorax and hindwings; increasing the friction that allows the parts to integrate into a whole; creating a buffer to protect the body from damage; and sensing the surrounding environment [21]. It remains unclear how beetles package their

• hindwings during folding into the tight space between the elytra and the abdomen. Improving our understanding of the directional friction locks that enable linkage between folded wing layers and between wings, movable elytra and the abdomen and of the morphology of microtrichia (length, width, distance

Single-step process to improve the mechanical properties of carbon nanotube yarn

• Maria Cecilia Evora,
• Xinyi Lu,
• Nitilaksha Hiremath,
• Nam-Goo Kang,
• Kunlun Hong,
• Roberto Uribe,
• Gajanan Bhat and
• Jimmy Mays

Beilstein J. Nanotechnol. 2018, 9, 545–554, doi:10.3762/bjnano.9.52

• . Covalent bonding among the tubes can be obtained via simultaneous functionalization and crosslinking [19]. Possible strategies for enhancing the friction between CNTs include modifying CNT surfaces through physical processes (e.g., condensing the tubes under high pressure) [16], chemical processes [20][21

Engineering of oriented carbon nanotubes in composite materials

• Razieh Beigmoradi,
• Abdolreza Samimi and
• Davod Mohebbi-Kalhori

Beilstein J. Nanotechnol. 2018, 9, 415–435, doi:10.3762/bjnano.9.41

• hard, solid or powder, biological, and organic or inorganic surfaces. This device can measure geometric morphology, adhesion distribution, friction, surface impurities, texture, elasticity, magnetism, chemical bonding forces, distribution of electric charges and electric polarization in different parts

• of the surface. In practice, this feature is used to study corrosion, cleanness, uniformity, roughness, adhesion, friction, size, etc. AFM, like SEM and TEM, is a suitable technique to characterize the alignment of CNTs, especially horizontal alignment; for instance, when the CNTs grow horizontally

Review: Electrostatically actuated nanobeam-based nanoelectromechanical switches – materials solutions and operational conditions

• Liga Jasulaneca,
• Jelena Kosmaca,
• Raimonds Meija,
• Jana Andzane and
• Donats Erts

Beilstein J. Nanotechnol. 2018, 9, 271–300, doi:10.3762/bjnano.9.29

• -nanomanipulation techniques aimed to determine how changes in the contact electrode material and geometry of 2T NEM switch influence the device characteristics [8]. The very low coefficient of friction of Mo6S3I6 (0.03 [135]) could help to reduce surface wear originating from the tangential forces in the NEM

Exploring wear at the nanoscale with circular mode atomic force microscopy

• Olivier Noel,
• Aleksandar Vencl and
• Pierre-Emmanuel Mazeran

Beilstein J. Nanotechnol. 2017, 8, 2662–2668, doi:10.3762/bjnano.8.266

• (nanowear) have been reported in the literature [17][18][19][20], whereas AFM has been widely used for measuring nanoscale friction [21][22]. In this paper, we propose a new experimental methodology based on circular mode AFM (CM-AFM) to explore wear mechanisms and laws at the nanoscale. It consists of

• lateral force microscopy (LFM) signal proportional to the friction force) of the cantilever stemming from the circular displacement of the contact features a sinusoidal signal with the same frequency as the relative circular displacement of the contact. Then a lock-in amplifier is used to register the

• real-time amplitude of the LFM signal of the cantilever (or friction force) during the wear experiment in order to determine prospective variations of the friction properties during the experiment. For example, this option may be advantageously implemented for investigating the correlation between

Patterning of supported gold monolayers via chemical lift-off lithography

• Liane S. Slaughter,
• Kevin M. Cheung,
• Sami Kaappa,
• Huan H. Cao,
• Qing Yang,
• Thomas D. Young,
• Andrew C. Serino,
• Sami Malola,
• Jana M. Olson,
• Stephan Link,
• Hannu Häkkinen,
• Anne M. Andrews and
• Paul S. Weiss

Beilstein J. Nanotechnol. 2017, 8, 2648–2661, doi:10.3762/bjnano.8.265

• adds both a small, random contribution to the force on the atoms and a small friction factor that slows them down, aiming for an average total kinetic energy of the atoms that corresponds to the target temperature. The time step for molecular dynamics was 2 fs. To maintain the stability of hydrogen

• removal, the system was heated up to room temperature using the Langevin thermostat with a friction parameter of 0.002 s−1; the heating procedure was run for 2 ps in simulated time. The lowest layer of Au was fixed in its initial position to enable the removal of the thiolates. The pulling moved the

Interface conditions of roughness-induced superoleophilic and superoleophobic surfaces immersed in hexadecane and ethylene glycol

• Yifan Li,
• Yunlu Pan and
• Xuezeng Zhao

Beilstein J. Nanotechnol. 2017, 8, 2504–2514, doi:10.3762/bjnano.8.250

• slip length was inhibited by roughness at the micro-scale and effective friction increased. At the nano-scale, Schmatko et al. [16] studied boundary slip on the surfaces with varying coverages of grafted nanoparticles. They demonstrated that the slip length of hexadecane decreases from 150 nm to about

Numerical investigation of the tribological performance of micro-dimple textured surfaces under hydrodynamic lubrication

• Kangmei Li,
• Dalei Jing,
• Jun Hu,
• Xiaohong Ding and
• Zhenqiang Yao

Beilstein J. Nanotechnol. 2017, 8, 2324–2338, doi:10.3762/bjnano.8.232

• controlling the tribological behavior of friction pairs used in mechanical and biological engineering. In this study, by utilizing the method of three-dimensional computational fluid dynamics (CFD) simulation, the lubrication model of a friction pair with micro-dimple array was established based on the Navier

• total integration of the pressure is positive, which can increase the load-carrying capacity of a friction pair. The effects of the micro-dimple parameters as well as fluid properties on tribological performance were investigated. It was concluded that under the condition of hydrodynamic lubrication

• Reynolds number, there exists a combination of texture density and aspect ratio at which the optimum tribological performance could be obtained. Conclusions from this study could be helpful for the design of texture parameters in mechanical friction components and even in artificial joints. Keywords: CFD

Molecular dynamics simulations of nanoindentation and scratch in Cu grain boundaries

• Shih-Wei Liang,
• Ren-Zheng Qiu and
• Te-Hua Fang

Beilstein J. Nanotechnol. 2017, 8, 2283–2295, doi:10.3762/bjnano.8.228

• and adhesion when a probe touches the substrate) between Ni (probe) and Au (thin film substrate) under nanoindentation conditions using MD simulations. Moreover, Mulliah et al. [18] analyzed the friction coefficient, the dislocation, and related parameters of the nanostructure under nanoscratch

• interest. In this paper, the nanomechanical and grain boundary characteristics of Cu films were studied using MD simulations. The results are discussed in terms of the atomic trajectories, slip vectors, atomic flows, as well as the force and the average friction coefficients. Methodology The physical model

• ) divided by normal force (fz). As shown in Figure 16, the highest value of the average friction coefficient was observed for the grain boundary with a 20° angle. Therefore, in the case of vertical grain boundaries at different angles, it can be deduced that the structure strength of the grain boundary with

Fabrication of gold-coated PDMS surfaces with arrayed triangular micro/nanopyramids for use as SERS substrates

• Jingran Zhang,
• Yongda Yan,
• Peng Miao and
• Jianxiong Cai

Beilstein J. Nanotechnol. 2017, 8, 2271–2282, doi:10.3762/bjnano.8.227

• mechanical properties such as hardness, elastic modulus and friction coefficient. The fabrication of micro/nanostructures using the nanoindenter method can be also achieved. The shortcomings of this technique include low machining speed, small machining area and high cost, and thus the nanoindentation method

Velocity dependence of sliding friction on a crystalline surface

• Christian Apostoli,
• Giovanni Giusti,
• Jacopo Ciccoianni,
• Gabriele Riva,
• Rosario Capozza,
• Rosalie Laure Woulaché,
• Andrea Vanossi,
• Emanuele Panizon and
• Nicola Manini

Beilstein J. Nanotechnol. 2017, 8, 2186–2199, doi:10.3762/bjnano.8.218

• Trieste, Italy 10.3762/bjnano.8.218 Abstract We introduce and study a minimal 1D model for the simulation of dynamic friction and dissipation at the atomic scale. This model consists of a point mass (slider) that moves over and interacts weakly with a linear chain of particles interconnected by springs

• , representing a crystalline substrate. This interaction converts a part of the kinetic energy of the slider into phonon waves in the substrate. As a result, the slider experiences a friction force. As a function of the slider speed, we observe dissipation peaks at specific values of the slider speed, whose

• nature we understand by means of a Fourier analysis of the excited phonon modes. By relating the phonon phase velocities with the slider velocity, we obtain an equation whose solutions predict which phonons are being excited by the slider moving at a given speed. Keywords: atomic-scale friction; contact

A comparative study of the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively or negatively charged nanodiamonds

• Colin K. Curtis,
• Antonin Marek,
• Alex I. Smirnov and
• Jacqueline Krim

Beilstein J. Nanotechnol. 2017, 8, 2045–2059, doi:10.3762/bjnano.8.205

• the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively (hydroxylated) or negatively (carboxylated) charged nanodiamonds (ND). Immersion in −ND suspensions resulted in a decrease in the macroscopic friction coefficients

• to values in the range 0.05–0.1 for both stainless steel and alumina, while +ND suspensions yielded an increase in friction for stainless steel contacts but little to no increase for alumina contacts. Quartz crystal microbalance (QCM), atomic force microscopy (AFM) and scanning electron microscopy

• : additives; alumina; aqueous colloids; fractal; friction; lubricants; nanodiamond; nanotribology; quartz crystal microbalance; stainless steel; Introduction Interest in nanoparticles as eco-friendly lubricant additives has grown tremendously in recent years [1][2]. The field is driven in a large part by a

Imidazolium-based ionic liquids used as additives in the nanolubrication of silicon surfaces

• Patrícia M. Amorim,
• Ana M. Ferraria,
• Rogério Colaço,
• Luís C. Branco and
• Benilde Saramago

Beilstein J. Nanotechnol. 2017, 8, 1961–1971, doi:10.3762/bjnano.8.197

• polyethylene glycol (PEG) to lubricate Si surfaces. The friction coefficients were measured in a nanotribometer. The viscosity of the PEG + IL mixtures as well as their contact angles on the Si surface were measured. The topography and chemical composition of the substrates surfaces were determined with atomic

• ], 1-ethyl-3-vinylimidazolium [EVIM], 1-(2-hydroxyethyl)-3-methylimidazolium [C2OHMIM] and 1-allyl-3-methylimidazolium [AMIM] combined with the anions dicyanamide [DCA], trifluoromethanesulfonate [TfO], and ethylsulfate [EtSO4] were added to dry PEG. All additives (2 wt %) led to a decrease in friction

• tetrafluoroborate [BF4] and bis(trifluoromethylsulfonyl)imide [NTf2] mixed with propylene glycol dioleate to lubricate Al alloys. There was no impact on the friction coefficient but the wear rate was reduced significantly. The group of Liu [9][10][11][12][13] extensively investigated the role of ILs formed by

Stick–slip boundary friction mode as a second-order phase transition with an inhomogeneous distribution of elastic stress in the contact area

• Iakov A. Lyashenko,
• Vadym N. Borysiuk and
• Valentin L. Popov

Beilstein J. Nanotechnol. 2017, 8, 1889–1896, doi:10.3762/bjnano.8.189

• the stick–slip mode of boundary friction. An analytical description and numerical simulation with radial distributions of the order parameter, stress and strain were performed to investigate the spatial inhomogeneity. It is shown that in the case when the driving device is connected to the upper part

• of the friction block through an elastic spring, the frequency of the melting/solidification phase transitions increases with time. Keywords: boundary friction; dimensionality reduction; numerical simulation; shear stress and strain; stick–slip motion; tribology; Introduction The boundary friction

• mode occurs in tribological systems when the thickness of the lubricant layer separating two contacting surfaces is significantly smaller than the typical size of the surface roughness. At such a system configuration, the lateral motion of the friction surface is followed by a contact interaction

Nanotribological behavior of deep cryogenically treated martensitic stainless steel

• Germán Prieto,
• Konstantinos D. Bakoglidis,
• Walter R. Tuckart and
• Esteban Broitman

Beilstein J. Nanotechnol. 2017, 8, 1760–1768, doi:10.3762/bjnano.8.177

• nitrogen for 2 h and annealed. The elastic–plastic parameters of the materials were assessed by nanoindentation tests under displacement control, while the friction behavior and wear rate were evaluated by a nanoscratch testing methodology that it is used for the first time in steels. It was found that

• cryogenic treatments increased both hardness and elastic limit of a low-carbon martensitic stainless steel, while its tribological performance was enhanced marginally. Keywords: carbide refinement; cryogenic treatments; friction; nanoindentation; nanoscratch; wear-resistance improvement; Introduction AISI

• martensitic matrix [10]. This carbide refinement improved the macroscale wear resistance of the material by 35% under lubricated and by 90% under dry sliding conditions compared to the conventionally treated specimens [11]. A slight reduction in the macroscale friction coefficient has also been observed [11

The effect of the electrical double layer on hydrodynamic lubrication: a non-monotonic trend with increasing zeta potential

• Dalei Jing,
• Yunlu Pan and
• Xiaoming Wang

Beilstein J. Nanotechnol. 2017, 8, 1515–1522, doi:10.3762/bjnano.8.152

• reduce friction and wear. With respect to fluid lubrication, it can be divided into various regimes or states based on the thickness of the lubricant film, such as dry friction with a lubricant film thickness of ≈1–10 nm, boundary lubrication (≈1–50 nm), thin film lubrication (≈10–100 nm) and fluid film

Development of a nitrogen-doped 2D material for tribological applications in the boundary-lubrication regime

• Shende Rashmi Chandrabhan,
• Velayudhanpillai Jayan,
• Somendra Singh Parihar and
• Sundara Ramaprabhu

Beilstein J. Nanotechnol. 2017, 8, 1476–1483, doi:10.3762/bjnano.8.147

• spectroscopy. N-rGO-based nanolubricants are prepared and their tribological properties are studied using a four-ball tester. The nanolubricants show excellent stability over a period of six months and a significant decrease in coefficient of friction (25%) for small amounts of N-rGO (3 mg/L). The improvement

• nanolubricant in an induced draft (ID) fan results in the remarkable decrease in the power consumption. Keywords: friction; lubrication; nanolubricant; nitrogen-doped reduced graphene oxide; tribology; wear; Introduction Advances in machine technology necessitate the reduction in energy loss by improving the

• tribological performance. This energy loss is caused primarily by friction and wear. The employment of lubricants in machines reduces friction and wear, which results in energy saving. However, the tribological performance of conventional lubricants (water and oil) fails to meet the demand of newly developed

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

• two solid surfaces (force of adhesion per unit area) that governs contact stresses and strongly influences friction. In such method, the force, Fadh, required to separate a tip from a flat solid sample is measured. Subsequently, a single-asperity continuum contact mechanics model is used to extract

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

• treatment, this is not as practical since the lateral friction force is not controlled, so that the contact-mode treatment sometimes leaves broken leftovers around the area of interest (see Figure S8, Supporting Information File 1) and can damage the sample. On the origin of the surface aggregates The

The longstanding challenge of the nanocrystallization of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX)

• Florent Pessina and
• Denis Spitzer

Beilstein J. Nanotechnol. 2017, 8, 452–466, doi:10.3762/bjnano.8.49

• towards initiation by friction and electrostatic discharge for nanostructured 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) crystallized by spray flash evaporation (SFE), compared to the raw material (Table 1). The noticeably lower sensitivity towards friction can be based on the self-lubricating effect, as

• n-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (n-CL-20), which was less sensitive towards friction, impact and electrostatic discharge (Table 3). Klapötke has often experienced the influence of particle size on ESD, when stating for example ”the finer the powder of a particular (note

• impact and friction was reduced by two times, therefore questioning the reactivity. Nevertheless, further efforts were made to replace the bacterial cellulose with an energetic matrix. Crystallization in solution allows the formation of large crystals by growth, thus allowing more parametric studies

Biological and biomimetic materials and surfaces

• Stanislav Gorb and
• Thomas Speck

Beilstein J. Nanotechnol. 2017, 8, 403–407, doi:10.3762/bjnano.8.42

• -structured, flexible, hairy structures on their outer surfaces which can trap an air layer under water for time spans of several minutes, days and even months. The biological importance of these air layers may be buoyancy, insulation, oxygen supply during diving and/or friction reduction during swimming and

• diving. The main interest in biomimetic products lies in the potential friction reduction and in antifouling properties. For example, this could be practically implemented by covering the underwater parts of ship hulls with Salvinia effect coatings. Ongoing projects with ship builders aim to realize this