The CoO-MoO3-gamma-Al2O3 : VI. Sulfur content analysis and hydrodesulfurization activities

The sulfur uptake of commercial and laboratory prepared catalysts of the type MoO3¿-Al2O3, CoO¿-Al2O3 and CoOMoO3¿-Al2O3 was studied at 400 °C using H2/SH2 and thiophene/H2 as sulfiding gases. The temperature, time, and H2S partial pressure of sulfiding were varied, and the fraction of sulfur removable by H2 reduction at 400 °C was determined. The influence of the sulfur content on the activity for hydrodesulfurization of thiophene was also measured. Based on these findings the formation of MoS2 and Co9S8 as a result of the sulfidation is considered to be the most likely process, although the presence of small amounts of other sulfurcontaining species cannot be excluded. Experimental evidence is reported for the diffusion of Co2+ ions from the bulk towards the surface of the ¿-Al2O3 support during the sulfiding process. The hydrogenolysis activity was found to decrease with increasing sulfur content for the MoO3¿-Al2O3 catalyst, while on CoOMoO3¿-Al2O3 the reverse effect was observed

The CoO-MoO3-Al2O3 catalyst. IV. Pulse and continuous flow experiments and catalyst promotion by cobalt, nickel, zinc, and manganese

The activities of MoO3-Al2O3 catalysts promoted with various amts. of Co, Ni, Zn, and Mn were detd. in pulse and continuous flow expts. for the hydrodesulphurization of thiophene at atm. pressure and 400 Deg. The initial activities of a MoO3-Al2O3 and a CoO-MoO3-Al2O3 catalyst as inferred from pulse expts. are equal. Continuous flow expts. for all catalysts show that the activity decays rapidly and approaches a steady-state level that depends on the promoter and its concn. Max. steady-state activity levels are attained for each of the promoter ions at different metal-to-Mo ratios. Some models are discussed in an attempt to explain the exptl. results. A preliminary investigation of hydrogenation activity of the above-mentioned catalysts is reported. With increasing promoter content a min. for the initial hydrogenation activity is found. Hydrocarbon satn. at the steady-state is comparatively insensitive to the nature of the promoter ion, which may be associated with the sulphiding of the surface

The late endosomal adaptor molecule p14 (LAMTOR2) represents a novel regulator of langerhans cell homeostasis

Langerhans cells (LCs) are dendritic cells (DCs) residing in epithelia, where they critically regulate immunity and tolerance. The p14 adaptor molecule is part of the late endosomal/LAMTOR (lysosomal adaptor and mitogen-activated protein kinase and mammalian target of rapamycin [mTOR] activator/regulator) complex, thereby contributing to the signal transduction of the extracellular signaling-regulated kinase (ERK) and the mTOR cascade. Furthermore, p14 represents an important regulator for endosomal sorting processes within the cell. Mutated, dysfunctional p14 leads to a human immunodeficiency disorder with endosomal/lysosomal defects in immune cells. Because p14 participates in the regulation of endosomal trafficking, growth factor signaling, and cell proliferation, we investigated the role of p14 in mouse DCs/LCs using a conditional knockout mouse model. p14-deficient animals displayed a virtually complete loss of LCs in the epidermis early after birth due to impaired proliferation and increased apoptosis of LCs. Repopulation analysis after application of contact sensitizer leads to the recruitment of a transient LC population, predominantly consisting of short-term LCs. The underlying molecular mechanism involves the p14-mediated disruption of the LAMTOR complex which results in the malfunction of both ERK and mTOR signal pathways. Hence, we conclude that p14 acts as a novel and essential regulator of LC homeostasis in vivo

Isotherm and heat of adsorption in porous solids with defective pores-adsorption of argon and nitrogen at 77K in Saran activated carbon

The isotherm and isosteric heat of a porous solid are studied in terms of the local isotherms and isosteric heats of individual pores with defective walls, rather than graphitic walls as commonly assumed in the literature. We point out the incorrect formulas that have been used in the literature, and present a correct formula to calculate the isosteric heat for a porous solid. The correct formula is illustrated with a direct Monte Carlo ( MC) simulation of systems of two pores of different sizes, and finally we apply our theory to experimental data of argon and nitrogen adsorption at 77K on S600H and S84 Saran charcoals to derive their pore size distributions ( PSD). We show that the PSD derived from the fitting either the isotherm only or the heat curve only may not be reliable. It is necessary to utilize both the isotherm and heat curves in the derivation of a more reliable PSD. We also show that it is essential to use defected walls of carbon pores to model adsorption in pores as the model using graphitic walls can not describe isotherm and heat of adsorption adequately

Macrosegregation in directionally solidified dendritic alloys

In this article, gravity-driven flow and its subsequent effect of promoting macrosegregation during unidirectional solidification of dendritic alloys is presented. Examples of macrosegregation that arise during the controlled directional solidification of hypo- and hypereutectic Pb-Sn alloys are shown, and a method of preventing macrosegregation is demonstrated. The experimental work is discussed in terms of how current knowledge of solute redistribution in a dendritic array can be promoted as well as how the processing technique might be applied to improve microstructural homogeneity during controlled directional solidification