Exchanged atoms

Because it was not possible to explain the differences in the effectiveness of hydrogen as compared to other gases on the basis of differences in their physical properties, ie, thermal conductivity, diffusivity, or heat capacity differences, their chemical properties were explored. To differentiate between the hydrogen atoms in the C2H2 molecules and those injected as the quench, deuterium gas was used as the quench. The data showed that although 90% of the acetylene was recovered, over 99% of the acetylene molecules had exchanged atoms with the deuterium quench to form C2HD and... 

The reaction is carried out in close-loop reactor connected to a mass spectrometer for 1S02, 180160 and 1602 analyses as a function of time [38], The gases should be in equilibrium with the metallic surface (fast adsorption/desorption steps 1 and f ) If the bulk diffusion is slow (step 6) and the direct exchange (step 5) does occur at a negligible rate, coefficients of surface diffusion Ds can be calculated from the simple relationship between the number of exchanged atoms Ne and given by the model of circular sources developed by Kramer and Andre [41] ... 

If there is more than one exchanging atom of X in the interacting molecules, for example AX exchanging with BX , the rate expression (1.191) is modified accordingly, with a and b replaced by na and mb respectively. This applies only when the nX or mX atoms are equivalent. In basic solution the vanadium(V) ion, exchanges oxygen with solvent... 

Probing Nucleic Acid-Ion Interactions with Buffer Exchange-Atomic Emission Spectroscopy... 

The ion atmosphere of nucleic acids directly affects measured biochemical and biophysical properties. However, study of the ion atmosphere is difficult due to its diffuse and dynamic nature. Standard techniques available have significant limitations in sensitivity, specificity, and directness of the assays. Buffer exchange-atomic emission spectroscopy (BE-AES) was developed to overcome many of the limitations of previously available techniques. This technique can provide a complete accounting of all ions constituting the ionic atmosphere of a nucleic acid at thermodynamic equilibrium. Although initially developed for the study of the ion atmosphere of nucleic acids, BE-AES has also been applied to study site-bound ions in RNA and protein. 

To overcome the limitations of other techniques, buffer exchange-atomic emission spectroscopy (BE-AES) was created (Bai et al, 2007). Measurements of the ion atmosphere done with BE-AES provide a rigorous thermodynamic measure of the number of ions associated with a nucleic acid. BE-AES is sensitive to a wide number of elements and has proven to... 

To emphasize the layer stmcture and show why hydrogen could be exchanged without dismpting the layer, Kautsky336) drew the part of formula which represents the layer surrounded by a rectangle. All exchangeable atoms are then outside this box ... 

Let us first discuss a system which is traditional for optical pumping in the Kastler sense [106, 224, 226], namely an optically oriented alkali atom A (see Fig. 1.1) in a noble gas X buffer surrounding. It is important to take into account the fact that in alkali atoms, owing to hyperfine interaction, nuclear spins are also oriented. However, in a mixture of alkali vapor with a noble gas alkali dimers A2 which are in the 1SJ electronic ground state are always present. There exist two basic collisional mechanisms which lead to orientation transfer from the optically oriented (spin-polarized) atom A to the dimer A2 (a) creation and destruction of molecules in triple collisions A + A + X <—> A2 + X (6) exchange atom-dimer reaction... 

If there are n exchangeable atoms in a molecule then a =. The equi-... 

In order to accomplish what I above alluded to as a desideratum for the explanation of chemical reactions, namely effecting between the formulae of the reagents the interchange supposed to take place in the mixture, I have fixed the symbols of those atoms which have to change places upon the extremities of a piece of card, so fixed by a pivot to the board that by turning round 180 it reverses the positions of the exchanging atoms. 

Double decomposition (double replacement) Two compounds decompose, exchanging atoms to form two new compounds... 

Let Z be the overall number of oxygen molecules of arbitrary isotopic composition which has already exchanged atoms per time/unit on the surface of a catalyst (molecules/cm -sec). In order to form a molecule with mass 34(0i 0 ) molecules with masses 0 and O2 should participate in the exchange. The probability of such a phenomena to the accuracy of isotopic effects is equal to... 

Here K is the number of oxygen molecules exchanging atoms according to the mechanism considered in (molecules/cm sec) is the content of 0 in the oxygen of the catalyst surface. 

Here -fiTs is a number of oxygen molecules exchanging atoms following the third mechanism. 2a5(l —a ) is an equilibrium fraction of molecules relative to the isotopic composition of the surface layer of catalyst. 

A double-replacement reaction, on the other hand, involves two compounds undergoing a "change of partners." Two compounds react by exchanging atoms to produce two new compoimds ... 

Figure 12 Bandwidth, artefacts, and baseline. Pulse sequences previously tested in Figure 11 were applied to a sample of 10 mM N-acetyl-asparagine (98% D2O) in order to evaluate the effects of the various suppression methods on exchangeable atoms (amides), resonances close to the solvent (HaS), and extremely intense peaks (acetyl group).

A number of semiempirical GGA exchange functionals, which contain parameters obtained by fitting the exchange atomic energies have been proposed. Roughly speaking, these functionals can be divided in two main classes. In the first one, we may group those which can be considered as modifications of the functional proposed by Becke in 1988 [25] (hereafter referred to as B), whose enhancement factor can be expressed as... 

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