Search

Polytetrafluoroethylene (PTFE) is a polymer that is well known for its exceptional tribological properties and, as such, it is commonly used to reduce the coefficient of friction between surfaces. In recent years it has also been established that by incorporating nanoparticle fillers in PTFE, it is possible to extend the polymer's life by reducing its wear rate. Although much study has been placed on bulk PTFE, very little study has been focused on thin films. This article demonstrates that SiO2 nanoparticles can be used as a filler to significantly reduce the wear of PTFE thin films while also maintaining a low coefficient of friction. The wear resistance and coefficient of friction of PTFE/SiO2 composite films on stainless steel substrates were tested using a linear reciprocating tribometer and compared to pure PTFE films and bare stainless steel to evaluate the benefit of incorporating the SiO2 filler in the film. The composite films showed a significant improvement in wear resistance when compared to pure PTFE films. The coefficient of friction for the composite film remained low and stable during a 50 g normal load friction test for a duration of approximately 300 cycles, whereas that of PTFE showed an increasing trend at onset. In addition, of 1.7 and 3.3 wt% SiO2 concentrations in solution, 3.3 wt% SiO2 showed better performance, with a much higher wear resistance than that of 1.7% SiO2 after being subjected to a 1,000-cycle abrasive wear test. [ABSTRACT FROM AUTHOR]

Spectral karyotyping (SKY) represents an effective tool to detect individual chromosomes and analyze major karyotype abnormalities within an entire genome. We have tested the feasibility of combining SKY and FISH/protein detection in order to combine SKY’s unique abilities with specific loci detection. Our experimental results demonstrate that various combined protocols involving SKY, FISH and immunostaining work well when proper procedures are used. This combined approach allows the tracking of key genes or targeted chromosome regions while monitoring changes throughout the whole genome. It is particularly useful when simultaneously monitoring the behavior of both protein complexes and DNA loci within the genome. The details of this methodology are described and systematically tested in this communication. Copyright © 2001 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]