Titanium single electron transistor fabricated by electron-beam lithography

A new method to fabricate non-superconducting mesoscopic tunnel junctions by oxidation of Ti is presented. The fabrication process uses conventional electron beam lithography and shadow deposition through an organic resist mask. Superconductivity in Ti is suppressed by performing the deposition under a suitable background pressure. We demonstrate the method by making a single electron transistor which operated at $T < 0.4$ K and had a moderate charge noise of $2.5 \times 10^{-3}$ e/$\sqrt{\mathrm{Hz}}$ at 10 Hz. Based on nonlinearities in the current-voltage characteristics at higher voltages, we deduce the oxide barrier height of approximately 110 mV.Comment: 6 pages, 4 figure

Spin-orbit Scattering and the Kondo Effect

The effects of spin-orbit scattering of conduction electrons in the Kondo regime are investigated theoretically. It is shown that due to time-reversal symmetry, spin-orbit scattering does not suppress the Kondo effect, even though it breaks spin-rotational symmetry, in full agreement with experiment. An orbital magnetic field, which breaks time-reversal symmetry, leads to an effective Zeeman splitting, which can be probed in transport measurements. It is shown that, similar to weak-localization, this effect has anomalous magnetic field and temperature dependence.Comment: 10 pages, RevTex, one postscript figure available on request from [email protected]

Influence of tungsten carbide particle size and distribution on the wear resistance of laser clad WC/Ni coatings

Thick composite coatings of carbides (e.g. WC) in a metal matrix are ideal for components subject to heavy abrasive wear. An emerging deposition technique for such wear resistant cemented carbide coatings is laser cladding. This technique has, contrary to surface welding and spraying methods, the potential to coat very locally and on highly complex components. Adhesion and damage resistance is also improved by laser cladding. In this paper the influence of carbide particle size and distribution on the wear resistance of laser clad coatings is discussed. A nickel based matrix reinforced with WC/W2C carbides is deposited by a CO2 laser on low carbon steel substrates. Different coatings are made with three different particle sizes of the carbides and volume fractions ranging from 0 up to 50%. Three different wear modes are evaluated. First, ball-on-disc tests with an Al2O3 ball have been performed. The ball cratering test with 4 mum SiC abrasive is used to assess mild abrasive wear. Finally, the resistance against severe two body abrasion is tested in a pin-on-disc test. A clear dependency of the wear resistance on the carbide concentration is found, which is more pronounced for the coatings with the finest WC/W2C carbides. The magnitude of the decrease in wear however is highly dependent on the wear mode. In two body abrasion and in the sliding wear, a small amount of carbides is sufficient to improve the wear resistance drastically. Other coating characteristics such as microstructure, hardness and internal stress are assessed. (C) 2004 Elsevier B.V. All rights reserved.status: publishe

Education through organised youth sport: The results of four Dutch studies

The main goal of this series of four studies was to examine the contribution of organised youth sport to adolescents’ antisocial and prosocial behaviour, and to gain insight into educationally relevant factors that were hypothesized to explain differences in antisocial and prosocial behaviour among athletes that could be attributed to characteristics of the sporting environment were studied in three cross-sectional studies, using multilevel regression analyses, followed by an intervention study. A total of N = 1030 male and female athletes, aged 9 tot 19 years, who were members of 54 competitive swimming, football, basketball, athletics and taekwondo clubs, participated in four consecutive empirical studies. Summarising the results of the four studies, we concluded that organised youth sport substantially contributed to the behaviour of the young athletes. Moral reasoning, moral atmosphere and fair play attitude were identified as factors having a positive educational value for young athletes, but the coach was found to exert the greatest socialising influence. The final conclusion is that efforts to enhance the educational quality of organised youth sport should focus on equipping coaches with the skills to develop and to maintain good relationships with their young athletes