Supported gold nanoparticles are highly selective catalysts for a range of both liquid-phase and gas-phase hydrogenation reactions. However, little is known about their stability during gas-phase catalysis and the influence of the support thereon. We report on the activity, selectivity, and stability of 2-4 nm Au nanoparticulate catalysts, supported on either TiO2 or SiO2, for the hydrogenation...

Hypocalcemia and resistance to exogenous parathyroid hormone have been reported in several clinical states associated with magnesium deficiency. On the basis of such observations, it has been suggested that magnesium depletion per se may result in impaired responsiveness of the adenyl cyclase-adenosine 3',5'-monophosphate (3',5'-AMP) system. To test this hypothesis, 4 wk old male parathyroidect...

Sonochemical preparation of Co and Ni promoted MoS(2) supported on alumina was achieved by high-intensity ultrasonic irradiation of isodurene solutions containing molybdenum carbonyl, dicobalt octacarbonyl, elemental sulfur, and Al(2)O(3) or Ni-Al(2)O(3) under Ar flow. The sonochemically prepared catalysts were characterized by elemental analysis, XPS, SEM, TEM, and XEDS, and hydrodesulfurizati...

The scientific literature provides extensive evidence of widespread magnesium deficiency and the potential need for magnesium repletion in diverse medical conditions. Magnesium is an essential element required as a cofactor for over 300 enzymatic reactions and is thus necessary for the biochemical functioning of numerous metabolic pathways. Inadequate magnesium status may impair biochemical pro...

The photosynthetic gene cluster of R sphaeroides is encoded on a 45kb region of the genome and is represented by 8 overlapping inserts cloned in the mobilisable vector pSUP202 [ l ] . Characterisation of the cluster by a variety of techniques, including complementation analyses and study of accumulated products of bacteriochlorophyll synthesis in mutants, provides a physical map (Figure 1) and ...

using c2h2, 112 and as gases at 550'c, carbon nanotubes were fabricated on the surfaces of twosubstrates coated by nano thin layers of metal catalysts by dc magnetron sputtering. aystamless steel andfe/cteal, by thermal chemical vapor deposition (tcvd) the surface properties of the substrates wereparticularly investigated, and the effect of treatment of the substrates on the cnt's growth is cri...

Metal ions are known to act as catalytic centres in metallo-enzymes. On the other hand, low-molecular-weight metal complexes are widely used as catalysts in chemical systems. However, small catalysts do not have a large protein ligand to provide substrate selectivity and minimize catalyst poisoning. Despite the challenges that the lack of a protein ligand might pose, some success in the use of ...

The first steps of oseltamivir synthesis from quinic acid involve acetalization and ester formation. These reactions are catalyzed by either acids or bases, which may be accomplished by heterogeneous catalysts. Sulfonic solids are efficient acid catalysts for acetalization and esterification reactions. Supported tetraalkylammonium hydroxide or 1,5,7-triazabicyclo[4.4.0]dec-5-ene are also effici...