Ion–ion recombination coefficients were measured at pressures ranging from 50 to 800 Torr for four oxygen–nitrogen mixtures which had been passed through cold traps at temperatures just above the boiling points of the gas samples. The following values of α were obtained at 1 atm and 25 °C: in O2, (2.00 ± 0.10) × 10−6 cm3/sec; air, (2.21 ± 0.10) × 10−6 cm3/sec; N2 with 1% O2, (2.24 ± 0.10) × 10−6 cm3/sec; N2 with 0.001% O2, (2.45 ± 0.15) × 10−6 cm3/sec. The observed pressure dependence of α followed that predicted by Natanson's theory.Considerably lower values of about 1.6 × 10−6 cm3/sec were found for untreated air, and a further reduction to about 1.4 × 10−6 cm3/sec was observed when surfaces, which had been coated with a colloidal suspension of graphite in alcohol, were present.
A low cost, real time method of measuring the movement of the ribcage and abdomen during anaesthesia is described. The equipment comprises a scanning light stripe system, video pre-processing electronics and a personal computer. Selected chest surface contours are measured at the rate of 2Oms per contour. Linear interpolation is used to provide contour area estimates between contour sample periods to allow chest volume to be calculated at 2Oms intervals. Results using test objects show that the equipment is able to measure volume to an accuracy of beuer than 1 % with reproducibility to within 0.3%
An analytical expression is proposed to simulate the effects of pH and redox potential (E) on the sorption of uranium onto model inorganic particles in aquatic environments instead of following an experimental approach providing a list of empirical sorption data. The expression provides a distribution coefficient (Kd) as function of pH, E and ligand concentration (complex formation) applying a surface complexation model on one type of surface sites (>SuOH). The formulation makes use of the complexation and hydrolysis constants for all species in solution and those sorbed at the surface, using correlations between hydrolysis constants and surface complexation constants, for the specific sorption sites. The model was applied for the sorption of uranium onto aluminol, iron hydroxide and silanol sites, mimicking respectively 'clean' clay or 'dirty' clay and 'clean' sand or 'dirty' sand ('dirty' referring to iron hydroxide contaminated), in absence or presence of carbonates in solution. The calculated distribution coefficients are very sensitive with the presence or absence of carbonates. The Kd values obtained by applying the model are compared with values reported in the literature for the sorption of uranium onto specific adsorbents. It is known that in surface water, U(VI) and its hydroxides are the primary stable species usually observed. However, reduction to U(IV) is possible and may be simulated during sorption or when the redox potential (E) decreases.Similar simulations are also applicable to study the sorption of other redox sensitive elements.
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