Terminology : vidéo programme

Endoscopists have for some time now been feeling the necessity of defining and uniforming terms and definitions in digestive endoscopy. Some time ago, OMED published a manual by Prof. Maratka, that represents an important reference point to overcome this problem. Our idea to produce on video endoscopic terminology, on the lines of Prof. Maratka's book, arose with the event of electronic endoscopy, which we have been using since May 1985. The electronic instrument certainly offers more didactic possibilities than the traditional fiberscope, consenting enlarged and highly definable pictures. So far, we have produced the first videotape, regarding "Fundamental terms and Definitions". The video terminology programme will be completed within the end of 1992 with 4 more videotapes entitled : esophagus, stomach, pancreas and biliary tract and colon

Understanding uranium behaviour in a natural rockâwater system: leaching and adsorption tests on the Tufo Rosso a Scorie Nere ignimbrite (Viterbo area, central Italy)

Based on both chemical leaching and adsorption tests and a simple modelling using PHREEQC, geochemical behaviours of uranium during the ignimbriteâwater interaction were evaluated mainly as a function of temperature, pH, and solution chemistry (esp., alkalinity). The main results of this work are: (1) uranium is more easily mobilized by slightly basic solution (pH 7.5) than by acidified water (pH 4.5) when relative concentrations of the main uranyl ionâcalciumâcarbonate species, Ca2UO2(CO3)3, increase from 0.6 to 90%; (2) the greatest leaching of uranium occurs at 50 °C (not at higher temperature) because the first dissociation constant of H2CO3 is directly correlated with temperature up to about 50 °C, but decreases from 50 to 80 °C. This directly influences the concentration of HCO3â which is mirrored by dissolved CO2 variations; (3) the presence of alkalinity, total C-species and calcium controls the saturation index of sorbate solution with respect to calcite, influencing also speciation, solubility, and sorption of dissolved U; and (4) higher adsorption of uranium is obtained in tests with deionized water (90.0 ± 0.7 mg/kg, at equilibrium) compared to those performed with the natural water (26.0 ± 1.5 mg/kg, at equilibrium), strengthening the role of complexes between uranyl, HCO3â, and Ca2+ ions in solution to explain the corresponding decrease in uranium adsorption

Crystal-chemistry of non-metamict pyrochlore-group minerals from Latium (Italy)

We here present results of a crystal-chemical study of a suite of pyrochlore-group minerals front the holocrystalline syenitic ejecta scattered within the Plio-Pleistocene pyroclastic deposits of Latium, in central Italy. Despite their high actinide content, the samples Studied are non-metamict owing to their young age of formation, as suggested by the well-defined and sharp peaks in the X-ray powder-diffraction pattern. The measured a unit-cell dimension is correlated with the (Ti + Fe3+) content at the B site of the structure. Following the IMA classification scheme for pyrochlore-group minerals modified according to the "50% rule" adopted in 1992, the samples are classified as betafite, pyrochlore and uranpyrochlore. In comparison with known data for pyrochlore-group minerals. the samples have extremely high Ti contents (tip to 81.3 atom % Ti relative to the Ti + Nb + Ta sum) and significant and variable contents of Zr (up to 8.44 wt.% ZrO2) and W (up to 12.14 Wt-% WO3). Some crystals display strong compositional zoning, consistent with the substitution 3Nb(5+) + Na+ reversible arrow 3Ti(4+) + U4+. The accommodation of extremely high amounts of W6+ can be related to the coupled substitution 2(Nb + Ta)(5+) reversible arrow Ti4+ + W6+ at the B site. Pyrochlore-group minerals from Latium have significantly high REE contents (up to 7.75 wt.% oxide). Chondrine-normalized patterns follow the general trend typical of unaltered pyrochlore. i.e., with an extreme Ce-enrichment and a decrease toward the heavy REE

Radiometric dating of Light Non-Aqueous Phase Liquids (LNAPLs) dispersed in soil: A low environmental impact tool for natural resource restorations and protection

Non-polar liquids released in environment cause a long-term soil and groundwater contamination. The costs associated with a multi-year remediation are high and the uncertainty in the allotment of legal responsibilities could defer the decontamination planning. Therefore, a reliable method to assess the residence time of spilled Non-Aqueous Phase Liquids (NAPLs) in soil is highly needed. In this paper, a method, using low environmental radioactivity and radiometric dating, is described and applied to real contaminations. After being alpha-recoiled from 232Th in soils,228Ra accumulates in light NAPLs, generating 228Th. A disequilibrium clock, based on γ-spectrometric determination of the ratio 228Th/228Ra, was conceived to measure the residence time of LNAPL pollutants in a soil. The pollutant extraction and γ-counting procedures are described. This approach inverts the role played by pollutants and contaminated matrixes, because the flux of alpha recoil from soil generates in pollutants a reliable model of “closed system”, which is preserved in LNAPLs due to the peculiar properties of non-polar liquids. All case studies are sited in Italy and have been supported by preliminary lab tests. Dating tests of 15 samples (including LNAPLs, contaminated soils and oil socks) were performed, in most cases, blindly. Then, the results were compared to historical data about contaminations. A good correlation between test results and site history was generally obtained. But an increasing error has to be considered in old contaminations due to the nonlinear nature of disequilibrium time equation. Other reasons of discrepancies, due to system opening, include the use of surfactants, the presence of significant amount of MnO2 in soil and the interactions of different spillages. The outcomes of this research evidence the possibility to precisely date the contamination both in soil and in non-polar liquids, offering a potential tool to settle legal disputes. Further studies could broad and improve the applicability of the method