Oxygen surface interactions with

In this complex the molecule is quasi parallel to the surface and the two adjacent interacting sites could be the Na+ ion linked to Cj and the oxygen atom interacting with one proton of C3. 

During the period of selective reduction of nitrobenzene to nitrosobenzene, the most likely intermediate is a surface species of which only one of the two oxygen atoms interacts with the oxide surface, possibly as shown in structure II. Direct evidence for this adsorption mode could not be obtained by FT-IR spectroscopy, most probably because the lifetime of this mode is too short to allow its observation. 

Fig. 14. Nicotinamide-binding site of Lactobacillus casei dihydrofolate reductase. NADPH is indicated by its van der Waals surface. The oxygen atoms of isoleucin-12, threonine-45, and alanine-97 that are involved in enthalpically favorable oxygen-aromatic interactions with NADPH are labeled.

The oxidation of pyrite can occur when the mineral surface is exposed to an oxidant and water, either in oxygenated or anoxic systems, depending on the oxidant. The process is complex and can involve chemical, biological, and electrochemical reactions. The chemical oxidation of pyrite can follow a variety of pathways involving surface interactions with dissolved O2, Fe, and other mineral catalysts (e.g., Mn02). Oxidation of pyrite... 

We have recently reported that cerium-exchanged mordenite (CeNa-MOR) is a higjily active and selective catalyst for NO reduction witli ammonia in oxygen-rich conditions [23]. We have furtlier found tliat it oxidizes SO2 to a negligible extent [24, 25], and tliat it appears to flilfill the aforementioned requirements for an ideal NH3-SCR catalyst. In the present paper, we will report on these aspeets of eerium-exchanged zeolite catalysts. Furthermore, its surface interaction with two reactants, NO and NH3, is examined with the temperature programmed desorption (TPD) technique. 

These 5- l bonds are largely responsible for the oval shape of uncomplexed valinomycin. Moreover, they direct two of the ester carbonyl oxygens toward the surface of the molecule (see Fig. 4). These might serve as initiators of complex formation by interaction with the metal ion prior to the placement of the latter in the ligand cavity. Based on this assumption. Smith and Duax developed a simplified model for the complexation process They proposed that the formation of the initial loose complex with the potassium ion is followed by cleavage of both the 5->l type hydrogen bonds in order to enable all the other ester carbonyl oxygens to interact with the cation and to replace the molecules of its solvation shell one after another. 

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