Influence of surface wettability on friction and wear test.

In this work the effect of surface wettability of different materials on friction and wear behaviour with sliding friction of 100% has been studied. The following materials have been chosen: AISI 1050 and AISI 420 steels, pyrex glass, teflon PTFE. and carbon fiber. All have different surface wettability angles u .. Tests with these materials have been carried out with a pin-on-disc tribometer with homogeneous and heterogeneous couplings in dry conditions and with oil and water lubrication. The most important result achieved with the mechanical tests and the SEM examinations is that with couplings of a hydrophillic and a hydrophobic material, water lubrication has a greatly positive effect. Particularly with hydrophobic discs and hydrophillic pins the friction factor and the wear have been lower than those with oil lubrication

[Alarm signals in ultrasound evaluation of the gestational sac]

The author stresses the importance of the echographic morphology of the gestational sac in evaluating pathological first-trimester pregnancies. The various ovular alarm signals are indicated and the abortion percentages are correlated to the various echographic patterns. The methods enables us to formulate a prognostic judgement which is both sufficiently valid and more closely consistent with the clinical reality