Tanabe model

The Tanabe model for acidity prediction in mixed oxide compositions is based on the interaction of the oxides at molecular level, the interaction generates an excess of negative or positive charge in the mixed composition localized around the guest element. According to this model, the substitution/introduction of a metal ion into... 

Fig. 3.9 Vertical profiles of DDT concentration [ng/L] in the Pacific ocean close to Japan (A),(B), in the Indian ocean (E), and in the Antarctic ocean (F). Model results in comparison with observations from Tanabe and Tatsukawa (1983).

Stier P, Feichter J, Kinne S, Kloster S, Vignati E, Wilson J, Ganzeveld L, Tegen I, Werner M, Balkanski Y, Schulz M, Boucher O, Minikin A, Petzold A (2005) The aerosol-climate model ECHAM5-HAM. Atmos Chem Phys 5 1125-1156 Tanabe S, Tatsukawa R (1983) Vertical transport and residence time of chlorinated hydrocarbons in the open ocean water column. Journal of the Oceanographical Society of Japan 39 53-62 Tiedtke M (1989) A comprehensive mass flux scheme for cumulus parameterization in large scale models. Mon WeaRev 117 1779-1800... 

Figure 8-20 MolScript ribbon drawings of the OmpF porin of E. coli. (A) View of the 340-residue monomer. (B) View of the trimer looking down the threefold axis. From Wa-tanabe et al3is From atomic coordinates of Cowan et al.3i9 (C) Molecular model of the constriction zone of the PhoE porin. Locations of key residues are shown, with positions of homologous residues in OmpF given in parentheses. Extracellular loops have been omitted. Constructed from coordinates of Cowan et al.349 by Samartzidou and Del-cour.342 Courtesy of Anne Delcour.

Much work has been done to characterize surface and catalytic properties of Si02—A1203 and other mixed-oxide systems. It is well known from these studies that Si02—A1203 possesses Lewis as well as Br nsted acid sites that are interconvertible. Different models for the site structures have been proposed. Tanabe 20) has recently reviewed these attempts to characterize the surfaces of silica-alumina mixed oxides as well as those of crystalline silica-aluminas. 

G. -M. Schwab History of Concepts in Catalysis. -J. Haber Crystallography of Catalyst Types. -G.Froment, L. Hasten Catalytic Kinetics Modelling. -A J. Lecloux Texture of Catalysts. - K Tanabe Solid Acid and Base Catalysts. 

No general rules for predicting the basic character of mixed oxides have been proposed up to now. On the contrary, qualitative models have been developed concerning the generation of new acidic features upon mixing different oxides. The models most frequently cited are those developed by Tanabe [79] and Kung [80]. 

Later, a number of studies attempted to determine the nature of acid sites in the catalyst. Also applying XPS and IR spectroscopy, Tanabe and others proposed a structure of chelating bidentate complexes, in which the sulfate species chelates to a single Zr atom [102, 146]. This model, a chelating bidentate species, was also proposed by Ward and Ko [61]. 

Tanabe has reviewed the earlier work with silica-magnesia, silica-zirconia, and other amorphous siliceous materials. In a model for binary siliceous oxide catalysts, only the non-siliceous component was considered in terms of proton affinity and co-ordination number. Tanabe and co-workers " proposed a general model for mixed oxide catalysts in which acidity is caused by an excess of negative or positive charge in a model structure of the binary oxide. The hypothesis is shown to fit 28 of the 31 binary oxides tested. One of these oxides,... 

Source of Activity in other Strongly Acidic Oxides.—While surface acidity is found to some degree in many oxides, relatively few show strong acidity comparable with that of the various siliceous materials considered above. Earlier work on these oxide systems has been reviewed by Tanabe and he later proposed a general model for acidic binary oxide catalysts. 

Tsuyoshi Tanabe, Tomoko Kuwabara, Masaki Warashina, Kenzaburo Tani, Kazunari Taira and Shigetaka Asano, Oncogene inactivation in a mouse model. Nature, 406 (2000), 473. 

According to Tanabe [288] in an o ersimplified model for acid-base bifunctional catalysts the distance between a basic site (O) and an acid site (M) in the catalyst surface. should be similar to that between the basic site (B) and the acidic one (A) in the molecule to be transformed (Figure 27. cases I and 2). Therefore, a concerted mechanism occurs. If the distance M-O is lower or higher than the distance B-A. the process w ill not be possible (Figure 27 cases 3 and 4). 

Fukush E, Tanabe S, Watanabe M, Kawabata J (1998). NMR analysis of a model pentapeptide, acetyl-Gln-Gln-Gln-Pro-Pro, as an epitope of wheat allergen. J. Magn Reson. Chem., 36 10 741-746. 

Oshita H, Tanabe TA (2000) Water migration phenomenon model in cracked concrete. II. Calibration. J Eng Mech-ASCE 126 544... 

Michaluart, R, Masfeirer, JL., Carothers,AM.,Subbaiamaiah, K., Zweifel, B.S., Koboldt, C., Mestre, J.R., Grunberger,D., Sacks, P.G., Tanabe, T., and Dannenbetg, A J. (1999) Inhibitory Effects of Caffeic Add Phenethyl Ester on the Activity and Expression of Cyclooxygenase-2 in Human Oral Epithelial Cells and in a Rat Model of Inflammation, Cancer Res. 59,2347-2352. 

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