[Pleuroperitoneal communication: pleural effusion subsequent to the initiation of peritoneal dialysis, about a case]. / Communication pleuro-péritonéale : épanchement pleural consécutif à la mise en route d'une dialyse péritonéale, à propos d'un cas.

We report the case of a patient with pleural effusion occurring after initiation of a peritoneal dialysis. This phenomenon is favoured by the existence of a pleuroperitoneal communication. The latter is described at the origin of other diseases like catamenial pneumothorax and pleural effusion in connection with cirrhotic ascites. We describe this rare complication of peritoneal dialysis in order to draw attention of nephrologists, pulmonologists and surgeons.

Nous rapportons le cas d'un patient présentant un épanchement pleural après mise en route d'une dialyse péritonéale. La cause de ce phénomène est l'existence d'une communication pleuro-péritonéale. Cette dernière est décrite à l'origine d'autres pathologies comme le pneumothorax cataménial et l'épanchement pleural dans le cadre d'ascite cirrhotique. Nous décrivons cette complication rare de la dialyse péritonéale dans le but d'attirer l'attention des néphrologues, pneumologues et chirurgiens sur celle-ci.

Origin of the decoherence of the extended electron spin state in Ti-doped ß-Ga2O3.

The mechanism of decoherence of the electron spin of Ti(3+) in ß-Ga2O3 was investigated by pulsed electron paramagnetic resonance. At 4.2 K, both instantaneous and spectral diffusion contribute to the decoherence. For electron spin concentrations ≈10(25) m(-3) in the studied samples, calculations indicate that electron-electron couplings and electron couplings with (69)Ga and (71)Ga nuclei yield similar contributions to the spectral diffusion, but that electron-nuclei interactions could become the dominant cause of spectral diffusion for only slightly lower spin concentrations. Above 20 K, an additional contribution to the decoherence as well as to the spin-lattice relaxation arises from a two-optical-phonon Raman process, which becomes the leading decoherence mechanism for T > 39 K. Rabi oscillations with a damping time of about 79 ns at 4.2 K could also be observed. The damping of the Rabi oscillations, independent of the oscillation frequency, is suspected to arise from electron-nuclei interactions.

Dating carbonaceous matter in archean cherts by electron paramagnetic resonance.

Ancient geological materials are likely to be contaminated through geological times. Thus, establishing the syngeneity of the organic matter embedded in a mineral matrix is a crucial step in the study of very ancient rocks. This is particularly the case for Archean siliceous sedimentary rocks (cherts), which record the earliest traces of life. We used electron paramagnetic resonance (EPR) for assessing the syngeneity of organic matter in cherts that have a metamorphic grade no higher than greenschist. A correlation between the age of Precambrian samples and the shape of their EPR signal was established and statistically tested. As thermal treatments impact organic matter maturity, the effect of temperature on this syngeneity proxy was studied; cyanobacteria were submitted to cumulative short thermal treatment at high temperatures followed by an analysis of their EPR parameters. The resulting carbonaceous matter showed an evolution similar to that of a thermally treated young chert. Furthermore, the possible effect of metamorphism, which is a longer thermal event at lower temperatures, was ruled out for cherts older than 2 Gyr, based on the study of Silurian cherts of the same age and same precursors but various metamorphic grades. We determined that even the most metamorphosed sample did not exhibit the lineshape of an Archean sample. In the hope of detecting organic contamination in Archean cherts, a "contamination-like" mixture was prepared and studied by EPR. It resulted that the lineshape analysis alone does not allow contamination detection and that it must be performed along with cumulative thermal treatments. Such treatments were applied to three Archean chert samples, making dating of their carbonaceous matter possible. We concluded that EPR is a powerful tool to study primitive organic matter and could be used in further exobiology studies on low-metamorphic grade samples (from Mars for example).

Site-selective electron nuclear double resonance in the exchange-narrowed regime of the ESR in conducting solids.

Electron nuclear magnetic double resonance on conduction electrons reveals the hyperfine interaction hidden by the fast electron spin exchange. We used the Overhauser shift technique to investigate the electron spin density of the conduction band of gallium oxide, beta-Ga(2)O(3). Due to the monoclinic structure, the conduction band of beta-Ga(2)O(3) is anisotropic and it is dominated by contributions from the two nonequivalent Ga sites. The large quadrupole couplings of the two gallium isotopes (69)Ga and (71)Ga (both with I = 3/2) are completely resolved in our double-resonance experiments. This resolved quadrupole interaction allows the determination of the electric field gradients at both gallium sites with high precision and high sensitivity. The resolved quadrupole splitting is the key to the site-selected determination of the hyperfine interaction. The concepts behind these double-resonance techniques are rather general and should be applicable in similar semiconductor systems.