The simultaneous chemisorption of hydrogen and carbon monoxide on zinc oxide

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Effect of Micropore Filling on Chemisorption by Large Surface Area Materials. Adsorption of O2 and N2O by CuZnO Catalysts

In irreversible chemisorption by large surface area catalysts, the partially covered surface takes up additional amounts of adsorbate only if a given threshold pressure is attained. A model is suggested in which micropore filling acts as a precursor state for other gas-solid interactions. The model is applied to the adsorption of oxygen by CuZnO catalysts with various copper contents, and containing particles and interparticle voids of various sizes

Genetic dissection of fruit quality traits in the octoploid cultivated strawberry highlights the role of homoeo-QTL in their control

Fruit quality traits are major breeding targets in the Rosaceae. Several of the major Rosaceae species are current or ancient polyploids. To dissect the inheritance of fruit quality traits in polyploid fleshy fruit species, we used a cultivated strawberry segregating population comprising a 213 full-sibling F1 progeny from a cross between the variety ‘Capitola’ and the genotype ‘CF1116’. We previously developed the most comprehensive strawberry linkage map, which displays seven homoeology groups (HG), including each four homoeology linkage groups (Genetics 179:2045–2060, 2008). The map was used to identify quantitative trait loci (QTL) for 19 fruit traits related to fruit development, texture, colour, anthocyanin, sugar and organic acid contents. Analyses were carried out over two or three successive years on field-grown plants. QTL were detected for all the analysed traits. Because strawberry is an octopolyploid species, QTL controlling a given trait and located at orthologous positions on different homoeologous linkage groups within one HG are considered as homoeo-QTL. We found that, for various traits, about one-fourth of QTL were putative homoeo-QTL and were localised on two linkage groups. Several homoeo-QTL could be detected the same year, suggesting that several copies of the gene underlying the QTL are functional. The detection of some other homoeo-QTL was year-dependent. Therefore, changes in allelic expression could take place in response to environmental changes. We believe that, in strawberry as in other polyploid fruit species, the mechanisms unravelled in the present study may play a crucial role in the variations of fruit quality

Adsorption of Sulfur Compounds by Hydrodesulfurization Catalysts

The adsorption of benzene and dibenzothiophene by hydrodesulfurization catalysts in oxidic and sulfided states has been measured. The equilibrium isotherms were Langmurian, with the adsorption capacity depending on the size of the adsorbate molecule and determined by the area of the adsorbing surface. Sulfidation created an increase in the adsorbing area and in the adsorption capacity. It also caused a strengthening of the adsorption bond involving the heteroatom and inhibition of bonds involving the benzene ring. The kinetics were in agreement with a model based on activated surface diffusion in the pores. The energy of activation for diffusion was related to the strength of the adsorption bond when the adsorbate was taken up from the gaseous phase. The adsorption of dibenzothiophene from the liquid phase was too slow to be measurable when the catalyst was in an oxidic state but proceeded at a measurable rate on the sulfided catalyst

Kinetics of Soil chemical Reactions : relationships between empirical equations and diffusion models, Soil Sci.Soc. Am

ABSTRACT A variety of kinetic equations such as zero-order, first-order, second-order, Elovich, fractional-power, and parabolic-diffusion equations have been used to describe the kinetics of soil chemical processes. Often, several of these expressions seem to equally well describe the kinetics of a particular reaction. In this research, it is shown that the kinetics of phosphate sorption/release can be described by an expression that is approximated at beginning times by a fractional-power equation, at intermediate times by the Elovich equation, and at long times by an apparent first-order equation. Such kinetics, which can be characterized by a sigmoidal z(f) plot of the reciprocal of the rate against the time l(dq/dt)-' vs. t], are consistent with theoretical homogeneous and heterogeneous models based on diffusion of the sorbate in the solid phase or at the solid/liquid interface. These models were applied to data from the published literature on sorption and release of phosphates by soils. For some soils, the experimental results were accounted for by assuming a constant diffusion coefficient. For other soils, it was assumed that diffusion processes with various diffusion coefficients take place simultaneously. Using these models, diffusion parameters can be estimated. A N ARRAY of kinetic equations including zero-, first-, and second-order, Elovich, fractional-power, and parabolic-diffusion equations have been employed over the years to describe the kinetics of soil chemical phenomena (Sparks, 1989). In several cases, a number of these equations seem to equally well describe time-dependent data if simple correlation coefficients and standard errors of the estimate are the indices that are used to evaluate the data (Chien and Clayton, 1980; Onken and Matheson, 1982; Sparks and Jardine, 1984; Havlin et al., 1985). The following expressions often describe time-dependent data well: 1. The fractional-power or modified Freundlich equation, which can be expressed as q = kf [1] where q is the amount sorbed, k and v are constants and v is positive and smaller than one, and t is time. This expression is generally considered empirical, except for the case in which v = 0.5, where it becomes indistinguishable from the parabolic-diffusion equation. Equation [1] and various modified forms of this equation have been applied to experimental data by several researchers (Cooke, 1966; Kuo and Lotse