Diffusion in the matrix

It is worth noting that one of the great advantages of the matrix technique is that trace impurities are rarely a problem because there is little or no diffusion in the matrix. Recently Bonneau and Kelly Q ) have obtained definitive results on this solution system, partly by reference to data obtained in solid matrices (21), which suggest that saturated perfluorocarbons should interact with Cr(C0)5 less than other practicable room temperature solvents. Thus, Bonneau and Kelly have investigated the laser flash photolysis of Cr(C0>5 in perfluoromethylcyclohexane (C7F14) at room-temperature. A transient species 620 nm) formed... 

Conventional Systems. In the conventional antifouling compositions, the organotin compound (TBTO, TBTF, TBTC1, TBTOAc) is mechanically mixed into the paint vehicle. When the TBT species is completely soluble in the polymer matrix, factors (a) and (b) become unimportant in most cases. The mobile species is already present its diffusion in the matrix, phase transfer and migration across the boundary layer into the ocean environment may be represented by Figure 2a. When the organotin compound forms a dispersed second phase, rate of its dissolution in the polymer matrix becomes another factor to consider. 

Our experimental data, when fitted to this equation, yield a value of 1.0 x 10-11 cm2/sec for Di. Least square fit of the same data to Crank s rate equation, which takes into account only the diffusion in the matrix, evaluates Dj to be 2.2 x lO-1 1 cm2/sec. The integral form of Crank s equation (13), giving the cumulative amount released per unit surface area,... 

Birgersson, L., and I. Neretnieks, Diffusion in the matrix of granitic rock. Field test in the Stripa mine. Water Resources Research 26 p 2833-2841, 1990... 

If this were generally the case, it is good news for the retardation of solutes such as radionuclides that can be considerably retarded during their transport from a repository to the biosphere. They would be given much more time to decay. The effect can be very strong because an increase in the FWS by a factor x gives the factor x influence on the mean travel time of a species that diffuses in the matrix. 

This simple synthesis of vinylidene lb allowed to study its reactions with a variety of small molecules. [30] To allow bimolecular reactions in rigid inert gas matrices, at least one of the reactants has to diffuse in the matrix. As descri-... 

Pick s laws also describe diffusion in solid phases. In solids transport properties can be considerably different than in liquid phases. Only one component can mobile diffuse in the matrix of the second component. At higher temperatures the diffusion coefficient can be more similar in size than in liquid phases, but the diffusion coefficient at room temperature can be orders of magnitudes smaller, e.g., D < 10 ° cm s k To overcome the time limitation one must make the diffusion length smaller. Ultra-thin layers or nanoparticles provide such small dimensions. Under such conditions the diffusion is not semi-infinite but has a restricted extension. This has to be considered in the boundary conditions. 

In instances when the inert gas atoms are incorporated into the solids without their parent isotopes diffusion in the matrix is the main mechanism for the gas release from solids. In instances when the parent nuclides of the inert gas are... 

A vital requirement for effectiveness is limited compatibility (solubility) with the host polymer and controlled mobility (rate of diffusion) in the matrix. For polymers with a low glass transition temperature (such as polyolefins), continuous migration of the anti-static agent is important to achieve the desired effect, while for polymers with a glass transition rate considerably above ambient temperature (such as PVC, ABS, and polystyrene), the decisive factor is the compatibility at the moment of cooling. 

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