How to visualize quartz OSL signal components

The optically stimulated luminescence (OSL) signal of natural quartz measured under constant stimulation power (CW-OSL) is a featureless decay curve where underlying components cannot be identified easily. Visual interpretation of quartz OSL signals is easier if signals are shown in spectrum-like form. This can be achieved either through ramped stimulation, or by transforming a measured CW-OSL curve into a pseudo OSL curve. We show that both give similar results, but that transformation should be preferred as CW-OSL provides best signal-to-noise ratios. We present different transformation methods to obtain pseudo OSL curves and discuss the advantages and disadvantages of each method. In addition, we show that different pseudo OSL transformations can be used to emphasize specific aspects of the OSL signal. We conclude that transformation of CW-OSL to pseudo hyperbolically modulated OSL provides the most useful visualization of the quartz fast OSL component. Pseudo parabolic modulated OSL is the transformation of choice for showing the slow component(s). The pseudo OSL curves can be used for rapid visual inspection of the relative contribution of the OSL components prior to further analysis.     

Precision measurement of the wavelengths and natural line widths of 3d-2p pionic X-ray transitions in low-Z atoms

The wavelengths and the natural line widths of the 3d-2p transitions in the pionic atoms of ¹²C, ¹⁶O, ¹⁸O, ²⁴Mg, ²⁶Mg, ²⁸Si and ³⁰Si have been measured at SIN with a bent-crystal spectrometer. The precision reached in the transition wavelengths ranges from 4 to 18 ppm, and in the widths from 2 to 14%.     

Operator algebras and a theorem of Dieudonne

LetA be aC*-algebra with second dualA″. Let (φ _n)(n=1,...) be a sequence in the dual ofA such that limφ _n(a) exists for eacha εA. In general, this does not imply that limφ _n(x) exists for eachx εA″. But if limφ _n(p) exists whenever p is the range projection of a positive self-adjoint element of the unit ball ofA, then it is shown that limφ _n(x) does exist for eachx inA″. This is a non-commutative generalisation of a celebrated theorem of Dieudonné. A new proof of Dieudonné’s theorem, for positive measures, is given here. The proof of the main result makes use of Dieudonné’s original theorem.     

The application of the Wilhelmy balance to the measurement of electrocapillary effects in molten carbonate

In this work, the Wilhelmy method is shown to be very suitable for studying electrocapillary effects in molten salts. Unlike the optical methods usually used this method, can easily be used in automated set-ups. High accuracies of 0.3° in the contact angle were easily obtained. First experiments are reported on the electrocapillary effect on gold in molten carbonate under air. Small changes of 4° to 8° in the contact angle were found for potential excursions of –300 mV. At 650 °C a value of 65 ± 1° was obtained at Open Cell Voltage (OCV) which is in good accordance with the values found by Mugikura et al. and Matsumura et al. The wetting of gold by carbonate decreased at higher temperatures. In the literature, both positive and negative temperature effects have been reported, obtained in different gas atmospheres. Possibly the sign depends on the gas atmosphere used. However, this discrepancy can also be caused by differences in the characteristics of the gold surface used in the different studies. Received: 23 October 1997 / Accepted: 4 December 1997     

Comment on the Liouville equation and multisolitons

It has been asserted in the literature that a particular solution of the Liouville equation, ?_xtσ = e^σ, can be interpreted as an N-soliton. It is shown here that this solution id in fact familiar one-soliton written in a misleading form.     

Thermoluminescence emission characteristics of LiF(Mg,Cu,P) with different dopant concentrations

The spectrum of the light emitted during thermoluminescence from irradiated LiF(Mg,Cu,P) has been measured for samples with different Cu and P contents. The results show no essential differences in glow curve structure and emission spectrum for MCP materials with different dopant contents and produced with different production techniques, except for samples with a low phosphorus concentration. The emission spectrum consits of two bands with maxima at 350 and 384 nm; the latter is dominant in the main glow peak and the former becomes more important at higher temperatures. Both bands are correlated with phosphorus, which appears to play a vital role in the overall sensitivity.     

Lack of effect of an externally applied electric field on bacterial adhesion to glass

Deposition to glass of Streptococcus salivarius HB-C12 and Staphylococcus epidermidis 3399 in a parallel plate flow chamber in the absence and presence of an externally applied electric field has been studied experimentally. No effect on bacterial adhesion, including initial deposition rates, numbers of adhering bacteria after 4 h, spatial distributions of adhering bacteria and air bubble induced detachment, was found. A theoretical analysis shows that electric fields applied over a 150 μm thin glass substratum do not have a sufficiently strong effect on its surface potential to influence bacterial adhesion.