Three-body interactions in colloidal systems

We present the first direct measurement of three-body interactions in a colloidal system comprised of three charged colloidal particles. Two of the particles have been confined by means of a scanned laser tweezers to a line-shaped optical trap where they diffused due to thermal fluctuations. Upon the approach of a third particle, attractive three-body interactions have been observed. The results are in qualitative agreement with additionally performed nonlinear Poissson-Boltzmann calculations, which also allow us to investigate the microionic density distributions in the neighborhood of the interacting colloidal particles

White-etching matter in bearing steel. Part II: Distinguishing cause and effect in bearing steel failure

The premature failure of large bearings of the type used in wind turbines, possibly through a mechanism called “white-structure flaking”, has triggered many studies of microstructural damage associated with “white-etching areas” created during rolling contact fatigue, although whether they are symptoms or causes of failure is less clear. Therefore, some special experiments have been conducted to prove that white-etching areas are the consequence, and not the cause, of damage. By artificially introducing a fine dispersion of microcracks in the steel through heat treatment and then subjecting the sample to rolling contact fatigue, manifestations of hard white-etching matter have been created to a much greater extent than samples similarly tested without initial cracks. A wide variety of characterization tools has been used to corroborate that the white areas thus created have the same properties as reported observations on real bearings. Evidence suggests that the formation mechanism of the white-etching regions involves the rubbing and beating of the free surfaces of cracks, debonded inclusions, and voids under repeated rolling contact. It follows that the focus in avoiding early failure should be in enhancing the toughness of the bearing steel in order to avoid the initial microscopic feature event.Funding by CONACyT, the Cambridge Overseas Trust, and the Roberto Rocca Education Programme is highly appreciated and acknowledged.This is the accepted manuscript version. The final published version is available from Springer at http://link.springer.com/article/10.1007%2Fs11661-014-2431-x

(n,xn) measurements at 96 MeV

Double differential cross section for neutron production were measured in 96 MeV neutrons induced reactions at the TSL laboratory in Uppsala (Sweden). Measurements for Fe and Pb targets were performed using simultaneously two independent setups: DECOI-DEMON and CLODIA-SCANDAL. The double differential cross section were measured for an angular range between 15 and 100 degrees and with low-energy thresholds (1-2 MeV). Elastic distribution, angular distribution, energy distribution and total inelastic cross section were derived from measured double differential cross section. Results are compared with predictions given by several simulation codes and with other experimental data