DSA measurement

During an DSA measurement, the carrier gas (air, nitrogen or other gas) carries the inert gas released by the sample situated in a reaction vessels into a detector for the inert gas. For example, to measure the a-activity of radon, a scintillation counter, ionization chamber or semiconductor detectors can be used. On the other hand, / -activity measurements of Kr, are made by Geiger-Miiller tubes. Gamma-active radionuclides of xenon can be measured by a gamma-spectrometer. The stable nuclides of inert gases are measured by a mass spectrometer. 

The theoretical considerations summarized above indicate that the diffusion structural analysis can be applied to the investigation of processes taking place in solids or on their surfaces. Any process in a solid or its phase boundary leading to a change in either the surface and/or changes in the inert gas diffusivity (permeability) becomes observable from the DSA measurements. 

Inert gas diffusion parameters evaluated from DSA measurements reflect the mobility of inert gases in the solids, which can be used to determine the state of the defects in the solids. Inert gas atoms incorporated into solids are situated on the natural and/or artificial defects produced, for example, by ion bombardment, neutron irradiation or mechanical treatment. 

Miscellaneous. Iridium dioxide, like RUO2, is useful as an electrode material for dimensionally stable anodes (DSA) (189). SoHd-state pH sensors employing Ir02 electrode material are considered promising for measuring pH of geochemical fluids in nuclear waste repository sites (190). Thin films (qv) ofIr02 ate stable electrochromic materials (191). 

Figure 19. Variation in dimension of the X-fold cation site in alkali-feldspar for 2+ cations (), obtained by fitting the experimental data of Icenhower and London (1996) for Dca, >sr and Dsa at 0.2 GPa and 650-750°C. In performing the fits was set at 91 GPa for all runs. Error bars are 1 s.d. The positive slope is consistent with measured changes in metal-oxygen bond length from albite to orthoclase (cf Fig. 6). The solid line shows the best-fit linear regression given in Equation (35).

XPS has been used by several authors to identify the surface and bulk composition of ruthenium based, valve metal stabilized DSA electrodes for chlorine evolution. Augustynski et al. [45] investigated the composition of Ru02-Ti02 electrodes before and after electrochemical treatment. They found a surface composition which deviated significantly from that of the bulk. The Ru/Ti ratio corresponded to 0.15 at the surface while in the bulk 0.28 was measured. Similar results were obtained by De Battisti et al. [46] for Ru02-Ti02 electrodes with different composition ratios on Ti substrates. Fig. 10 shows the Ru/Ti ratio for different solution compositions as a function of the depth. 

Cure Kinetics. The cure kinetics of the mixed system to the B-stage were determined by the method outlined by Senich, MacKnight and Schneider (7) for two epoxy resins cured with dicyandianide by dynamic spring analysis (DSA). Senich et al. (7) used the elapsed time to the loss peak maximum of tan delta as a measure of the rate of the reaction at each temperature and for each frequency. The slope of an Arrhenius plot of In (tmax) vs. 1/T was then used to determine the activation energy. 

In differential thermal analysis (DTA), the temperature difference that develops between a sample and an inert reference material is measured, when both materials are subjected to an identical heat treatment [87], The related technique of DSA relies on differences in the energy required to maintain the sample and reference at an identical temperature. 

Drop shape analysis system DSA 10 (KRUSS) was used for contact angle measurements. X-ray Photoelectron Spectroscopy studies were performed on an ESCA 5700 from Physical Electronics. The S2P spectra were recorded from a sampling area of ca. 1 mm2 with a takeoff angle of 45° and analyzer pass energy of 29.35 eV. Acquisition times were ca. 9 min with a base pressure less than 5 x 10 10mbar. Spin coater model P 6700 series (Speedline Technologies) was used to prepare thin film... 

T25 to 181 C were examined by the DSA technique. Figure 2 shows the composite loss tangent response as a function of the natural logarithm of time for a cure at 147 C at several frequencies. Two tan 6 peaks are observed. At fixed temperature both peaks become smaller, shift to longer times, and exhibit Improved resolution as the frequency Is decreased. Figure 3 displays the composite loss tangent as a function of the natural logarithm of time at a fixed frequency of 3.5 Hz for cures at several temperatures. At this, the lowest frequency of measurement, the two peaks are best resolved, smallest, and occur soonest In time as the temperature is Increased. 

DSA analysis of Resin 5208 exhibits two dispersion regions. The first is related to gelation and the second is related to vitrification. The first DSA peak occurs on the attainment of a value for the resin storage modulus slightly lower than that of the rubbery plateau. The first TBA peak occurs at the point where the composite (braid and resin) attains measurable rigidity. 

Activation energies are derived from the dynamic mechanical experiments assuming that the kinetic mechanism does not change with temperature. The thus arrived at activation energy represents a lumped kinetic parameter for the reactions which have led to the point in time of the dynamics mechanical dispersion being measured. Activation energies for the first dispersion by DSA... 

Ability to use very low concentrations of compounds to be studied. For intramolecular ET in donor spacer acceptor (DSA) molecules, the ET rate that can be measured is independent of DSA concentration over a wide range. 

Surface and interfacial tensions of the two liquids were measured with a Kruss DSA 100 drop analyser system by the pendant drop method. The liquid was injected... 

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