RESUMO
In a laboratory that is working in many different fields, a systematic approach is needed to decide efficiently how a given analytical task should be handled. Four typical examples are presented to show how ICP-MS may be used to solve client's problems. The examples are: the identification of lead projectiles, the determination of total and leachable fractions of impurities in a polymer (PVDF), used for manufacturing components of ultrapure water distribution systems, the authentication of antique silver alloys, and the determination of rare earth elements in geological materials. These examples demonstrate not only typical challenges for the instruments and the analysts handling them, but also ways to reach a satisfactory solution within a reasonable amount of time.
RESUMO
Carbon fibre-reinforced polyetheretherketone (CF-PEEK) substrates were coated with titanium by vacuum-plasma-spraying and chemically treated in 10 M sodium hydroxide (NaOH) solution. After NaOH treatment, the specimens were immersed in simulated body fluid (SBF) containing ions in concentrations similar to those of human blood plasma. Scanning electron microscopy, energy-dispersive X-ray analysis and diffuse reflectance Fourier transformed-infrared spectroscopy were used to analyse the NaOH-treated VPS-Ti surface and the calcium phosphate layer formed during immersion in SBF. It was observed that a carbonate-containing calcium phosphate layer was formed on the NaOH-treated VPS-Ti surface during immersion in SBF, whereas no calcium phosphate precipitation occurred on the untreated surfaces. It is therefore concluded that vacuum-plasma-spraying with titanium and subsequent chemical modification in 10 M NaOH solution at 60 degrees C for 2 h is a suitable method for the preparation of bioactive coatings for bone ongrowth on CF-PEEK.
RESUMO
Plasma activation of polyetheretherketone (PEEK) surfaces and the influence on coating formation in a supersaturated calcium phosphate solution was investigated in this study. It was observed that plasma treatment in a N2/O2 plasma had a significant effect on the wettability of the PEEK surface. The contact angle decreased from 85 degrees to 25 degrees after plasma treatment. Cell culture testing with osteoblastic cell lines showed plasma activation not to be disadvantageous to cell viability. X-ray photoelectron spectroscopy (XPS) analysis was performed to characterize the chemical composition of the PEEK surfaces. It was observed that the O1s intensity increased with plasma activation time. At the C1s peak the appearance of a shoulder at higher binding energies was observed. Coating of PEEK was performed in a supersaturated calcium phosphate solution. Coating thicknesses of up to 50 microm were achieved after 24 days of immersion. Plasma activation followed by nucleation in a highly saturated hydroxyapatite solution had a positive effect on the growth rate of the layer on PEEK. Chemical analysis revealed that the coating consists of a carbonate-containing calcium phosphate.
RESUMO
This study centres around the question of how far the analysis of spruce needles (Picea abies L.) provides a suitable tool for detecting and describing large-scale air pollution, primarily by heavy metals, in Switzerland. For that reason 1637 spruce shoots from 833 sites were analysed, relationships between the different elements were calculated and maps of their spatial distribution drawn. The results show that needle analysis is a valid instrument for the identification of various air pollutants in Switzerland. The element best suited is Pb, followed by some others like Mo, Fe, Cd or S. The most heavily polluted areas in Switzerland are the midlands, and in the north and north-west. Their spatial distribution suggests that in these areas the indicator elements are derived from local sources.