Rate oscillations during partial oxidation of methane over chromel–alumel thermocouples

A chromel–alumel thermocouple has been found to catalyse the methane/oxygen reaction, the main products being CO, H2 with some CO2 and H2O. Regular oscillations in both reactants, products and temperature have been observed at temperatures around 700thinspcirC. Similar behaviour has been obtained using nickel wires

Synthesis and Characterisation of [Pd10(μ-CO)(μ3-CO)4(PEt3)6] and [Pd10(μ-CO)6(μ3-CO)2(μ-CNXylyl)2(PEt3)6]

The decanuclear palladium cluster compounds [Pdio(u-CO)g(^3-CO)4 (PEtglg] and [Pdio(/(-CO)g(ii3-CO)2(//-CNXyl)2(PEt3)g] (Xyl = CgH^M^- 2,6) have been synthesised and characterised by a combination of spectroscopic data and single crystal X-ray crystallographic analyses. The former has a distorted tetracapped octahedral skeletal geometry and the latter a hexacapped tetrahedral geometry. The latter is unique in cluster chemistry and the structural change induced by the addition of isocyanide represents an interesting example of the effect of the steric requirements of the isocyanide ligand influencing the total electron count and geometry of the cluster. [Pdio(/<-CO)8(/i3-CO)4(PEt3)g] reacts with SO2 to give [Pd5(/(-S02)2(p3-S02)2(PEt3)5]

Apparent equilibrium shifts and hot-spot formation for catalytic reactions induced by microwave dielectric heating

Microwave dielectric heating of the gas phase decomposition of H2S catalysed by metal sulfides on a -Al2O3 support results in significant apparent shifts in the equilibrium constant, which have been attributed to the development of hot-spots in the catalytic beds; X-ray diffraction and electron microscopy measurements have indicated the formation of hot-spots with dimensions of 90–1000 µm and which involve not only the active phase, but also the support

Determination of the nature of the Cu coordination complexes formed in the presence of NO and NH3 within SSZ-13

Ammonia-selective catalytic reduction (NH3-SCR) using Cu zeolites is a well-established strategy for the abatement of NOx gases. Recent studies have demonstrated that Cu is particularly active when exchanged into the SSZ-13 zeolite, and its location in either the 6r or 8r renders it an excellent model system for fundamental studies. In this work, we examine the interaction of NH3-SCR relevant gases (NO and NH3) with the Cu2+ centers within the SSZ-13 structure, coupling powder diffraction (PD), X-ray absorption spectroscopy (XAFS), and density functional theory (DFT). This combined approach revealed that, upon calcination, cooling and gas exposure Cu ions tend to locate in the 8r window. After NO introduction, Cu-ions are seen to coordinate to two framework oxygens and one NO molecule, resulting in a bent Cu-nitrosyl complex with a Cu-N-O bond angle of similar to 150 degrees. Whilst Cu seems to be partially reduced/changed in coordination state, NO is partially oxidized. On exposure to NH3 while the PD data suggest the Cu2+ ion occupies a similar position, simulation and XAFS pointed toward the formation of a Jahn-Teller distorted hexaamine complex [Cu(NH3)(6)](2+) in the center of the cha cage. These results have important implications in terms of uptake and storage of these reactive gases and potentially for the mechanisms involved in the NH3-SCR process

PET imaging of 18F-florbetapir in cognitively impaired individuals: Lack of activity within the cerebellar cortex

Ten individuals suspected of having possible Alzheimer disease underwent PET imaging using 18F-Flubetapir. Only one of ten individuals had a pattern typical for normal elderly control subjects with 9 of the 10 showing a Alzheimer type pattern for the cerebral cortex yet all 10 subjects had uniformly low to absent tracer localization to the cerebellar cortex; significantly high tracer activity was noted within the subcortical white matter of the cerebellum in a symmetric manner in all cases. In consideration of studies that have shown amyloid deposits within the cerebellar cortex in 90% of pathologically proven cases of Alzheimer’s disease, these findings raise questions about the actual clinical value of florbetapir PET imaging in evaluating cerebellar involvement and raises questions whether PET imaging of this tracer accurately portrays patterns of amyloid deposition, as there is rapid hepatic metabolism of the parent compound after intravenous injection. Possible links to Alzheimer’s disease related alterations in blood-brain barrier permeability to the parent compound and subsequent radiolabelled metabolites are discussed as potential mechanisms that could explain the associated localization of the tracer to the brainstem and subcortical white matter within the cerebrum and cerebellum of Alzheimer’s disease patients

Rapid detection of Ganoderma-infected oil palms by microwave ergosterol extraction with HPLC and TLC

Detection of basal stem rot (BSR) by Ganoderma of oil palms was based on foliar symptoms and production of basidiomata. Enzyme-Linked Immunosorbent Assays-Polyclonal Antibody (ELISA-PAB) and PCR have been proposed as early detection methods for the disease. These techniques are complex, time consuming and have accuracy limitations. An ergosterol method was developed which correlated well with the degree of infection in oil palms, including samples growing in plantations. However, the method was capable of being optimised. This current study was designed to develop a simpler, more rapid and efficient ergosterol method with utility in the field that involved the use of microwave extraction. The optimised procedure involved extracting a small amount of Ganoderma, or Ganoderma-infected oil palm suspended in low volumes of solvent followed by irradiation in a conventional microwave oven at 70 °C and medium high power for 30 s, resulting in simultaneous extraction and saponification. Ergosterol was detected by thin layer chromatography (TLC) and quantified using high performance liquid chromatography with diode array detection. The TLC method was novel and provided a simple, inexpensive method with utility in the field. The new method was particularly effective at extracting high yields of ergosterol from infected oil palm and enables rapid analysis of field samples on site, allowing infected oil palms to be treated or culled very rapidly. Some limitations of the method are discussed herein. The procedures lend themselves to controlling the disease more effectively and allowing more effective use of land currently employed to grow oil palms, thereby reducing pressure to develop new plantations.This project was supported by the Fundamental Research Grant Scheme (FRGS), administered through the Ministry of Higher Education, Malaysia (Grant No: 5524175)

Modern microwave methods in solid state inorganic materials chemistry: from fundamentals to manufacturing

No abstract available

Evidence of Hybrid Homogeneous–Heterogeneous Catalysis in a Pt/Au Heterobimetallic System

We report here our efforts towards understanding the catalytic species involved in a novel Pt/Au heterobimetallic system capable of efficiently catalyse the tandem cyclisation/C-X coupling reaction of heteroarylallenes with C- and N-based nucleophiles. Our evidence confirm that homogeneous Au-catalysis is involved at the beginning of the reaction to generate an intermediate that enters the second catalytic cycle where hybrid homogeneous-heterogeneous catalysis by [Pt-Au] clusters could be responsible for the high efficiency. In this part of the cycle [Pt-AuPPh3] homogeneous clusters (identified by 31P NMR) seem to be aided by Pt-Au particles in the heterogeneous phase (supported by Hg poisoning and filtration experiments, and characterization of the possible catalytic species by several techniques, e.g. 31P NMR, ICP-MS, SEM, DLS), with full Pt- to-Au transmetallation not being observed in contrast with other reported bimetallic systems. There are a few examples of hybrid homogeneous-heterogeneous catalysis in monometallic systems, but to the best of our knowledge this is the first example of hybrid homo- heterogeneous catalysis in systems involving two different metals