Measurement of the strength of brittle materials, such as resin composites, is extremely difficult. Micro-indentation hardness testing is a convenient way of investigating the mechanical properties of a small volume of material. In this study, the mechanical properties of five commercially available flowable resin composites were investigated by the dynamic micro-indentation method. Additionall...

We present a simple microscopic model describing the unique friction behavior of gecko setal arrays as they are dragged on smooth surfaces. Unlike other solids of high elastic modulus that do not stick under van der Waals forces alone, the gecko setal arrays do not require a compressive force to display a drag resistance but rather develop a tensile normal force when they are dragged (J. Experi...

Confined liquid crystals (LC) provide a unique platform for technological applications and for the study of LC properties, such as bulk elasticity, surface anchoring, and topological defects. In this work, lyotropic chromonic liquid crystals (LCLCs) are confined in spherical droplets, and their director configurations are investigated as a function of mesogen concentration using bright-field an...

The mechanical properties of concrete pavement were studied under the various frost-salt conditions using Capillary Suction of De-icing Chemicals and Freeze-thaw Test Method (CDF method). The test results show that: with the increasing of freeze-thaw cycles, concrete surface damage has a tendency to accelerate. The concrete which is in a 5% concentration chloride snow-thawing agent solution has...

We consider the 4d compact U(1) theory with Wilson action and characterize its phase diagram using the notion of electromagnetic flux, instead of the more usual magnetic monopole. Taking inspiration from the flux picture, we consider the helicity modulus (h.m.) for this theory, and show that it is an order parameter for the confinement deconfinement phase transition. We extend the definition of...

A simple globular-shaped liquid ~octamethylcyclotetrasiloxane, OMCTS! was placed between two rigid mica plates at variable spacings comparable to the size of this molecule and the linear shear viscoelasticity of the confined interfacial film was measured. Strong monotonic increase of the shear relaxation time, elastic modulus, and effective viscosity were observed as the spacing was decreased b...

The mechanical properties of sputter-deposited HfO2 and HfxSi1-xO2 films were studied as a function of composition using nanoindentation. The elastic modulus and hardness were measured at room temperature for as-deposited films of varying Hf content and for films subjected to annealing at 1000 C. The elastic modulus and hardness of as-deposited films were found to increase monotonically with in...

Article history: Received: 14.3.2013. Received in revised form: 23.12.2013. Accepted: 23.12.2013. This paper presents the microstructure, hardness and elastic modulus of Sn58Bi, Sn57Bi1Ag and Ag nanopowders reinforced Sn58Bi composite solders. Microstructural observations reveal that the Ag nanopowders reinforced Sn58Bi composite solders have smaller grains of Ag3Sn and a more uniform Ag3Sn dis...

Quintessential inflation is studied using a string modulus as the inflaton– quintessence field. It is assumed that the modulus crosses an enhanced symmetry point (ESP) in field space. Particle production at the ESP temporarily traps the modulus resulting in a period of inflation. After reheating, the modulus freezes due to cosmological friction at a large value, such that its scalar potential i...

Nano-scratch and nano-indentation were used to determine hardness, elastic modulus, adhesion, friction and wear resistance of chromium oxide coatings in air and in water. The friction coefficient is higher in water, compared to air, and it increases with the applied normal load, although there are no obvious differences in hardness and elastic modulus in air vs. water. A higher normal load incr...