A Crossed Electron-ion Beam Setup for Ionization Experiments

A new crossed beam experimental setup has been built for the study of electron impact ionization of multiply charged ions. The animated beam method has been applied. Sweeping irregularities and fluctuations of the beam intensities are taken into account. The electron gun is swept mechanically by means of a stepping motor. The energy range extends continuously from 20 eV to 6 keV. Results are reported for single and double ionization of Ar8+. The luminosity is seen to be of the order of 5 X 10(20) Hz/cm(2). The global performance of the present apparatus is compared with the one of similar devices

A new method of thermoablation with hot water vapour for localized tumours

BACKGROUND: A new method of thermoablation with hot water vapour based on a new type of microtube was developed. This approach allows tumours, with volume and anatomical positions not accessible to other techniques (cryoablation, radiofrequency ablation, laser ablation) to be treated. MATERIALS AND METHODS: The method was tested on a human colon carcinoma grafted subcutaneously in Swiss nude mice and the experiment monitored under magnetic resonance imaging. RESULTS: It was found that 2.52 cal s(-1) per cm3 of tumour were necessary to reduce tumour size. The microtube is built to withstand a large range of temperatures and pressures and is biocompatible. CONCLUSION: A specific feature of this technique is that, besides hot vapour, several types of drugs can be delivered through the same microtube depending of the location, type or size of the tumour. These properties make it a unique device for multi-therapeutic treatments

Electron impact ionization of argon ions (q=4-11)

Absolute cross sections for electron impact ionization of multiply charged argon ions (Arq+) have been measured in an animated crossed electron-ion beam experiment. Results are reported for single ionization (SI) (q = 4-6, 8, 10 and 11) ions and for double ionization (DI) (q = 5-11). The measurements cover the energy range from threshold to about 6000 eV The direct process is seen to dominate SI for q = 8, 10 and 11. For charge states 4-6, excitation-autoionization processes are seen to largely contribute to the ionization signal. In addition, metastable states are unambiguously identified for Ar5+ and Ar6+. Ionization-autoionization (IA) from the L shell accounts predominantly for DI of Arq+ (q = 5, 6). For charge states 7-11 direct DI is found to decrease strongly with respect to IA from the K shell

Elastic large-angle scattering of electrons by multiply charged ions

Differential cross sections for the elastic scattering of electrons by multiply charged ions have been measured at scattering angles between 32 degrees and 148 degrees. Mainly at backward angles the cross section deviates remarkably from the Rutherford cross section showing oscillations due to the structure of the ionic core. Experimental results obtained for Ar8+ ions and different Xe-q+ ions (3 less than or equal to q less than or equal to 6) are found to compare well with theoretical calculations

Intraarterial beta irradiation induces smooth muscle cell apoptosis and reduces medial cellularity in a hypercholesterolemic rabbit restenosis model

PURPOSE: Ionizing radiation has been shown to be a powerful inhibitor of neointimal hyperplasia following arterial injury in several animal models of post-percutaneous transluminal coronary angioplasty (post-PTCA) restenosis. This was previously shown to be associated with a reduction in smooth muscle cell (SMC) mitotic activity. This study evaluated the effect of intraarterial beta irradiation on the arterial wall SMC density and apoptosis. METHODS AND MATERIALS: Twenty-five carotid and 7 iliac arteries of hypercholesterolemic New Zealand white rabbits were injured using the Baumgartner technique. The impact of an 18 Gy beta radiation dose administered after balloon injury was studied and compared to a nonirradiated injured control group. The medial SMC density as well as the percentage of apoptotic cells were determined at 8 days, 21 days, and 6 weeks after injury using an automated computer-based software. Apoptotic cells were identified using in situ end-labeling of fragmented DNA. RESULTS: The values for medial apoptosis in control vs. irradiated arteries were: 0.014 +/- 0.023 vs. 0.23 +/- 0.28%, p = NS, at 8 days; 0.012 +/- 0.018 vs. 0.07 +/- 0.07%, p = 0.05, at 21 days; and 0 +/- 0 vs. 0.16 +/- 0.11%, p = 0.03, at 6 weeks. The overall incidence of medial apoptotic cells at all time points was 0.01 +/- 0.017 vs. 0.13 +/- 0.14% in controls and irradiated arteries respectively, p = 0.004. Medial SMC density was significantly decreased in irradiated arteries in comparison with controls (p < 0.01 at all time-points). CONCLUSIONS: Intraarterial beta irradiation stimulates medial SMC apoptosis in balloon-injured arteries. This, together with a decrease in SMC mitotic activity, contributes to a decrease in the arterial wall cellularity