PHOTOCATALYTIC DEGRADATION OF 4-CHLOROPHENOL MEDIATED BY TIO2 - A COMPARATIVE-STUDY OF THE ACTIVITY OF LABORATORY MADE AND COMMERCIAL TIO2 SAMPLES

The photocatalytic efficiencies of laboratory made and commercial TiO2 samples were compared using a standard test reaction: the photomineralization of 4-chlorophenol (4-CP) to CO2, H2O and HCl mediated by Degussa P25 TiO2 in a batch reactor. The results show that the rate of photodegradation of 4-CP, sensitized by a sample of TiO2, shows no clear simple dependence on physical characteristics such as the degree of crystallinity, the surface area and the percentage of H2O.

POSSIBLE NATURALLY-OCCURRING ZERANOL IN BOVINE BILE IN NORTHERN-IRELAND

Zeranol and two Fusarium toxins, alpha-zearalenol and beta-zearalenol, were confirmed by gaschromatography/mass spectrometry (GC/MS) in bovine bile samples referred to this laboratory for analysis. No evidence of zeranol abuse was found on-farm. Given the recent suggestion that zeranol might arise from the metabolism of these Fusarium toxins, and the finding of zeranol in bovine and ovine urine across the EU, it. was concluded that the residues had arisen as a result of natural metabolism.

EFFECTIVE LABORATORY MONITORING FOR THE ABUSE OF THE BETA-AGONIST CLENBUTEROL IN CATTLE

The use of the beta-agonist clenbuterol (CBL) as a growth promoter has been outlawed in European meat production. The detection of its illegal use is dependent on CBL residues persisting in animal tissues for longer than the withdrawal times given by abusers. A comparison of urine, bile and liver matrices indicated that analysis of the liver offered the best possibility for CBL detection. However, an experimental study showed that CBL detection following withdrawal could be further extended (up to 56 d) if the retina was used as the target tissue. Analysis of 703 retina and liver samples from cattle suspected of CBL medication revealed that 96 cattle had CBL residues present in their retinas, only 46 of these were liver positive. There were no instances of liver CBL residues being detected without the associated retina also being positive.

A review of Ni-like X-ray laser experiments undertaken using the VULCAN laser at the Rutherford Appleton Laboratory

Recent progress using the VULCAN laser at the Rutherford Appleton Laboratory to pump X-ray lasing in nickel-like ions is reviewed. Double pulse pumping with similar to 100 ps pulses has been shown to produce significantly greater X-ray laser output than single pulses of duration 0.1-1 ns. With double pulse pumping, the main pumping pulse interacts with a pre-formed plasma created by a pre-pulse. The efficiency of lasing increases as there is a reduced effect of refraction of the X-ray laser beam due to smaller density gradients and larger gain volumes, which enable propagation of the X-ray laser beam along the full length of the target. The record shortest wavelength saturated laser at 5.9 nm has been achieved in Ni-like dysprosium using double pulse pumping of 75 ps duration from the VULCAN laser. A variant of the double pulse pumping using a single similar to 100 ps laser pulse and a superimposed short similar to 1 ps pulse has been found to further increase the efficiency of lasing by reducing the effects of over-ionisation during the gain period. The record shortest wavelength saturated laser pumped by a short similar to 1 ps pulse has been achieved in Ni-like samarium using the VULCAN laser operating in chirped pulse amplified (CPA) mode. Ni-like samarium lases at 7.3 nm. (C) 2000 Academie des sciences/Editions scientifiques et medicales Elsevier SAS.

COLLISIONALLY EXCITED X-RAY LASER SCHEMES - PROGRESS AT RUTHERFORD APPLETON LABORATORY

Characteristics of the 3p-3s amplified spontaneous emission from Ne-like Ge plasma columns, generated by ablation from massive targets, have been studied in detail. In particular, the gain coefficients of the J = 2-1 lines at 23.2 and 23.6 nm have been measured as a function of incident intensity for a 1.05-mu-m wavelength pump laser beam. For 100-mu-m wide stripe targets and a fixed energy pump laser the maximum gain length product is achieved at an irradiance of

Laboratory measurements of 0.7 GG magnetic fields generated during high-intensity laser interactions with dense plasmas

We report measurements of ultrahigh magnetic fields produced during intense (similar to10(20) Wcm(-2) mum(2)) laser interaction experiments with solids. We show that polarization measurements of high-order vuv laser harmonics generated during the interaction (up to the 15th order) suggest the existence of magnetic field strengths of 0.7+/-0.1 GG in the overdense plasma. Measurements using higher order harmonics indicate that denser regions of the plasma can be probed. This technique may be useful for measurements of multi-GG level magnetic fields which are predicted to occur at even higher intensities.