Apparent surface

It was found in this work that the concentration of hydroxyl species on the surface determines the extent of Fe(C0)5 decomposition on Ti02 T e concentration of reduced titanium cations (T 3+) on the surface apparently has no effect on the process. Neither concentration affects the nature of the species formed. 

The van der Waals model of monomeric insulin (1) once again shows the wedge-shaped tertiary structure formed by the two chains together. In the second model (3, bottom), the side chains of polar amino acids are shown in blue, while apolar residues are yellow or pink. This model emphasizes the importance of the hydrophobic effect for protein folding (see p. 74). In insulin as well, most hydrophobic side chains are located on the inside of the molecule, while the hydrophilic residues are located on the surface. Apparently in contradiction to this rule, several apolar side chains (pink) are found on the surface. However, all of these residues are involved in hydrophobic interactions that stabilize the dimeric and hexameric forms of insulin. 

Bowden Yoffe have suggested (Ref 12, pp 127-128 Ref 14) that the abnormal sensitivity of NI3 or NI3 NH3 is due to its being inherently unstable, and that the very slight external stimuli (slight touch, warm air, irradiation etc) primarily act to remove adsorbed NH3 from the iodide surface. Apparently this adsorbed NH3 stabilizes the iodide and its removal causes the iodide to decompose spontaneously... 

Rehydration of the surface is found to be reversible only if the pretreatement temperature is kept below about 400°C. Above that temperature a restructuring of the surface apparently occurs. The removal of the H-bonded groups removes the adsorption site for water thus giving rise to a surface which does not adsorb water very readily at low pressure (Fig. 2). 

The exchange of NaBr and KBr with HC1 reaches an equilibrium in which, near to room temperature, a mixed Cl /Br surface is at equilibrium with a gaseous HCl/HBr mixture whose composition depends on the surface anion ratio, but which is typically about 1 mole % HBr. This equilibrium was discovered in the laboratory of one of us (LGH) about eighteen years ago [96], but the topic proved difficult to pursue because of the difficulty of quantitative analysis of the gas mixture. Eventually, a temperamental but workable gas chromatographic technique [97] having provided the key to this analysis, we were able to show that the equilibrium is highly non-ideal [98]. The bromide surface apparently undergoes a two-dimensional phase transition, induced by HC1 or HBr adsorption, close to room temperature, in which the halide ions become mobile,... 

In the case of Ba-]3-alumina [172] and La-P-alumina, the surface apparently only exposes the large low valency cations, detectable by adsorbing bases, and very basic oxygen species that adsorb CO2 in the form of carbonates. The decomposition temperature of surface carbonates on Ba-P-alumina (BaAli20i9) has been followed by IR under outgassing, and compared with the same experiment using MgO. BaAli20i9 appears to be far more basic than pure alumina and most pure oxides but less basic than pure alkaline earth oxides. 

In visualizing the molecidar configurations, we. sometimes observed that vapor molecules colliding with tlie lic uid surface apparently drove other molecules out of the liquid. This kind of correlation between 1 he condensation flux and the evaporation flux, or molecular e.xchange. may have a significant effect on the rate of condensation. Following... 

The dispersion described above is determined by the number and distribution of the amine complexing sites which in turn depend on the number and distribution of surface hydroxyl groups and steric constraints imposed by the pore size [Raman et al., 1993]. Modest reduction in helium and niuogen permeabilities as a result of the dispersion procedure seems to indicate that there is no significant particle penetration into the membrane pores and most of the catalyst deposition occurs on the membrane surface. Apparently, the reduced membrane pore size due to silylation prevents significant penetration of the large meial organic precursor molecules. 

In the PCM procedure Vei is expressed in terms of an apparent charge distribution a(s) which is spread on the cavity surface (Apparent Surface Charge method, ASC) ... 

Single tetralactam macrocycles on Au(lll) surfaces apparently only build disordered closed films, and clustering at step edges and surface defect sites occurs [145],... 

The zero-order kinetics imply saturated adsorption on the active part of the catalyst surface, while the adsorption on the whole surface apparently depends upon the pressure of formic acid. The saturated adsorption of the copper surface calculated as one-site adsorption is shown as 0 = 1 in the results. It appears therefore that the catalytically active part is a minor part of the surface available for adsorption. In this manner, adsorption measurements during surface catalysis in the case of a zero-order reaction could lead to an estimate of the active part of the catalyst surface. 

In catalytic combustion of a fuel/air mixture the fuel reacts on the surface of the catalyst by a heterogeneous mechanism. The catalyst can stabilize the combustion of ultra-lean fuel/air mixtures with adiabatic combustion temperatures below 1500°C. Thus, the gas temperature will remain below 1500°C and very little thermal NO. will be formed, as can be seen from Fig. 1. However, the observed reduction in NO. in catalytic combustors is much greater than that expected from the lower combustion temperature. The reaction on the catalytic surface apparently produces no NO. directly, although some NO.v may be produced by homogeneous reactions in the gas phase initiated by the catalyst. 

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