The changes in the mechanical properties and microstructure of nanocrystalline Cu-Zn alloys deformed by cryorolling during low temperature annealing and the post-process deformation were studied. The deformed Cu-Zn alloys exhibited uncommon anneal hardening and deformation softening behaviors. The degree of anneal hardening and deformation softening increased with the addition of the solute ato...

During the first stage of hardening of winter rape plants (Brassica napus L. var. oleifera L., cv. Górczański), marked increase of ATP content in leaves was observed. Lowering the temperature from 5 to 0 C (the second stage of hardening) had no further effect on ATP content. In roots, not capable of hardening, pronounced decrease of ATP content was noted after prolonged exposure to cold. It was...

It is well known that size effects are present in plasticity with the observation that smaller being the stronger. This effect is attributed to the presence of geometrically necessary dislocations (GNDs). The hardening associated to GNDs can be separated in two groups: energetic and dissipative. The fi rst is associated with defect energy and different defi nitions for it are possible. In all c...

Carbon nanotubes (CNTs) are well known for their exceptional thermal, mechanical and electrical properties. For many CNT applications it is of the foremost importance to know their frictional properties. However, very little is known about the frictional forces between an individual nanotube and a substrate or tip. Here, we present a combined theoretical and experimental study of the frictional...

Friction limits the operation of macroscopic engines and is critical to the performance of micromechanical devices. We report measurements of friction in a biological nanomachine. Using optical tweezers, we characterized the frictional drag force of individual kinesin-8 motor proteins interacting with their microtubule tracks. At low speeds and with no energy source, the frictional drag was rel...

Wepresent results from laboratory experiments and anumericalmodel for frictional weakening and shear localization. Experiments document strain localization in sheared layers at normal stresses of 0.5 to 5MPa, layer thicknesses of 3 to 10mm, and imposed slip velocities of 10 to 100 μm/s. Passive strain markers and the response to load perturbations indicate that the degree of shear localization ...

In this paper the ratcheting behavior of carbon steel(ASTM A106B) and stainless steel(304L) elbows is studied under steady internal pressure and in-plane external moments at frequencies typical of seismic excitations. The finite element analysis with the nonlinear isotropic/kinematic (combined) hardening model has been used to evaluate ratcheting behavior of the elbows. Material parameters have...

Lipids were labeled with (33)P during frost hardening of two varieties of winter wheat (Triticum aestivum), hardy Kharkov and much less hardy Champlein. The main labeled compounds were phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylglycerol. With time of incorporation the proportion of the radioactivity incorporated into the lipids increased in phosphatidyl...

X-ray computed tomography (CT) enables the visualisation and dimensional evaluation of both the internal and external geometry of a workpiece, it is therefore well suited for measuring geometric features that are otherwise inaccessible to tactile and optical instruments. Beam hardening is a wellknown physical process that can degrade the quality of CT images and influence edge detection algorit...