The Effect of Surface Site Ensembles on the Activity and Selectivity of Ethanol Electrooxidation by Octahedral PtNiRh Nanoparticles

Direct ethanol fuel cells are attractive power sources based on a biorenewable, high energy-density fuel. Their efficiency is limited by the lack of active anode materials which catalyze the breaking of the C−C bond coupled to the 12-electron oxidation to CO₂. We report shape-controlled PtNiRh octahedral ethanol oxidation electrocatalysts with excellent activity and previously unachieved low onset potentials as low as 0.1 V vs. RHE, while being highly selective to complete oxidation to CO₂. Our comprehensive characterization and in situ electrochemical ATR studies suggest that the formation of a ternary surface site ensemble around the octahedral Pt₃Ni₁Rh_x nanoparticles plays a crucial mechanistic role for this behavior.     

Diastereo-controlled Diels–Alder cycloadditions of erythrose benzylidene-acetal 1,3-butadienes by 4-substituted-1,2,4-triazoline-3,5-dione: Evidence for the stereoelectronic effects on the dienes

Erythrose benzylidene-acetal 1,3-butadienes are studied as partners in Diels–Alder cycloadditions. A high diastereofacial improvement is found in cases where both the alcohol function is protected and a π–π interaction between the diene and dienophile is possible. Several competing factors have been studied independently in order to explain its influence on the selectivity of the cycloadditions.     

Synthesis of alpha-galactosyl ceramide,a potent immunostimulatory agent

Alpha-galactosyl ceramide has been identified to be a potent stimulatory agent for a novel immunological process, mediated by CD1 molecules. This paper describes a short and efficient synthesis of alpha-galactosyl ceramide. Starting from commercially available 2-deoxy galactose, a suitable sphingosine derivative was obtained in nine steps and 36% overall yield, which was subsequently glycosylated to give the target molecule. This flexible route will provide various glycolipids for further exploration of this interesting biological process.     

Enhanced drainage and coarsening in aqueous foams

Experiments are presented elucidating how the evolution of foam microstructure by gas diffusion from high to low pressure bubbles can significantly speed up the rate of gravitational drainage, and vice versa. This includes detailed data on the liquid-fraction dependence of the coarsening rate, and on the liquid-fraction and the bubble-size profiles across a sample. These results can be described by a "coarsening equation" for the increase of bubble growth rate for drier foams. Spatial variation of the average bubble size and liquid fraction can also affect the growth and drainage rates.     

EPR detection of [Cu(mnt)X2]2−—A possible halogenide stabilized intermediate in ligand exchange reactions

During the reaction of [Cu(mnt)₂]^2? with CuX₂ (X = Cl, Br) [Cu(mnt)X₂]^2? species are formed and characterized EPR spectroscopically supporting a dissociative mechanism for ligand exchange reactions between [Cu(mnt)₂]^2? and other Cu(II), Ni(II) and Pd(II) complexes which contain unsaturated dichalcogeno ligands.     

Preliminary results on the immobilisation of radionuclides from waters with specific adsorbers based on phosphate salts

The present paper is focused on the ability of aluminium phosphate (ALPC), magnesium ammonium phosphate (MGPC), magnesium hydrogen phosphate (MGHPC), and calcium hydrogenphosphate (CAHPC), adsorbed onto charcoal, to immobilise actinides by adsorption from natural waters. The objective of this process is to evaluate the environmental pollution due to the actinides. Europium, thorium, protactinium, neptunyl, and uranyl ions were chosen to simulate actinides in the +3, +4, +5 and +6 oxidation state. The adsorbers were tested using natural waters samples. The adsorption trends and capacities were analysed. ALPC and MGPC exhibited a similar behaviour and adsorbed demonstrating that the +5, +4 and +3 actinide ions can be easily immobilised from natural waters and may be successfully used at pH 7-8. MGHPC may be used at a higher pH, whereas CAHPC is effective in the whole pH range. In all cases, thorium, protactinium and europium were strongly