Similar phases

In all cases except Li3Nb04, phases similar to Li4Nb04F and Li4Ta04F were found. Pure binary oxides transform easily to modified structures characterized by ordered cation distribution, while oxyfluorides are more stable and require treatment at a high temperature, for an extended period of time, in order to be transformed into a state of ordered cation distribution. 

Virtually all current research in SFC utilizes either small bore packed columns with particles of 5-10 micrometers in diameter optimized for use in liquid chromatography or narrow bore, fused silica open tubular columns with Immobilized phases similar to those used in gas chromatography. In the latter case columns of saaller internal diameter, 10-100 micrometers, shorter lengths (generally less than 20 m with 1-10 m being the most common length), and more firmly crosslinked stationary phases are used by coaparison with standard columns for gas chromatography. In all... 

In other experiments, PVC/plasticiser extracts (n-hexane) were separated by SEC using THF or chloroform as the mobile phase. Similarly, PE film was immersed in THF for several hours and the extract was concentrated by a factor of 20 prior to injection into a SEC system [51]. However, use of extraction techniques followed by injection into a SEC system for separation of low-MW additives is not the most obvious analytical approach in view of the relatively low resolution of conventional SEC in the low molecular mass range. For this purpose efficient column packing materials with small pore sizes are to be used. 

The tracer level Tc,nHA complex can be suspended as a colloid in an aqueous solution. Spedation of a similar complex, Am111 HA, in the Gorleben groundwater was performed by laser photoacoustic spectroscopy (LPAS) [33]. Considering its molecular size, however, migration of the complex is expected to be very slow when it is present in a solid phase. Similar LPAS studies of a technetium complex towards chemical spedation have been tried by our group in Sendai [36,37]. 

Another peculiarity of the study is that the use of a biological system has allowed the authors to hypothesize a possible mechanism of action of the leachate as a mixture, hypothesis that could have been drafted on the basis of the only knowledge derived by chemical analysis. Researchers suggest that leachate inhibits cell proliferation at low doses probably inducing a reversible cell cycle arrest that becomes irreversible at high doses, probably due to leachate-induced oxidative stress. This activity is mainly due to the chemical compounds extracted in the aqueous phase. Similar effects were noticed by previous investigations on other human cells (human peripheral blood lymphocytes and a human breast cancer cell line, MCF-7) [31, 32], supporting the hypothesis that cells that survive the initial insult from leachate constituents maintains the potential to proliferate until the effects on cell metabolism lead to death. 

Now suppose a smectic phase similar to the SmCA phase indicated in Figure 8.12 were an actual bilayer smectic with alternating synclinic and anticlinic layer interfaces, as illustrated in Figure 8.14a. It was already well... 

Peak plasma levels are reached about 1.5 h after oral ingestion, the maximum concentrations being in the order of 2 - 3 ng equivalents/ml (parent drug + metabolites) for an oral 1 mg dose. The elimination from the plasma is biphasic and proceeds with mean half-lives of 6 h (a-phase) and 50 h ((3-phase). Similar elimination half-lives are obtained from the urinary excretion. The cumulative renal excretion is practically the same after oral and intravenous administration and amounts to 6 - 7 % of the radioactivity dosed. The main portion of the dose, either oral or intravenous, is eliminated by the biliary route into the faeces. The kinetics of bromocriptine has been demonstrated to be linear in the oral dose range from 2.5 to 7.5 mg. 

On Pt(lll) the HREELS features due to water are unchanged by the presence of CO. These observations indicate that water and CO adsorb onto separate patches on the surface, in a form of hydrophobic coadsorption. Water condenses into hydrogen-bonded islands, as indicated by the low 0-H stretching frequency. CO spreads to cover the rest of surface, giving a phase similar to that for CO alone, but with a coverage normalized to the water-free, not total, surface area. COCO repulsions, which have been well documented on Pt(lll) (10), produce a surface pressure within the CO patches which bears upon the edges of the water islands. It is this lateral pressure which causes water to desorb from Pt(lll) at lower temperatures in the presence of coadsorbed CO. 

The fate of the bipyridinium radical cation in the mercaptan monolayer is not clear. The second reduction wave (Figure 3) possesses structure suggesting a precipitated phase similar sharp peaks are seen during the reductive precipitation of Cu.bpyMe2 ... 

The first study that made it possible to estimate the critical length of a column in gradient HPLC of proteins was presented by Belenkii and co-workers in 1993 [53]. Their approach was based on the concept of critical chromatography of synthetic polymers. They introduced the concept of a critical distance, X0, after which the protein zone travels with the same velocity as the mobile phase (similarly to what has been shown previously by Yamamoto et al. [60]). The equation for the critical distance at which the zone velocity v(x) becomes virtually identical to the displacer velocity, u, is defined as ... 

For a slow reaction occurring in the bulk liquid of phase 2, phase transfer and diffusion may not be rate limiting. Here, the reactants will enter phase 2 more quickly than they are consumed by the reaction, and thus become distributed at equal concentration throughout this phase (see Figure 2.13a). In this case the rate of the reaction in phase 2 will be described by Equation 2.3, with the rate of reaction being directly proportional to the concentration of the reactants in phase 2 and uniform throughout the phase. Similarly, for a slow reaction occurring at the phase boundary, the rate of diffusion of the reactants will exceed their... 

Sorption/desorption is one of the most important processes influencing movemement of organic pollutants in natural systems. Sorption with reference to a pollutant is its transfer from the aqueous phase to the solid phase on the other hand, desorption is its transfer from the solid phase to the aqueous phase. Similar to all interphase mass-transfers, the sorption/ desorption process can be defined by the final-phase equilibrium of the pollutant at the aqueous-solid phase interface and the time required to approach final equilibrium. 

Analysis using a CMPA is usually resolved on a nonchiral column. A transient diastereomeric complex is formed between the enantiomer and the chiral component in the mobile phase, similar to the complexes formed with chiral stationary phases. A review by Liu and Liu (2002) cites several papers where addition of CPMAs has been used in analyzing amphetamine-related compounds. Some CPMAs include amino acid enantiomers, metal ions, proteins, and cyclodextrins. Advantages of this method of analysis include the use of less expensive columns and more flexibility in the optimization of chiral separation (Misl anova and Hutta, 2003). 

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