An embedded atom method study of the equilibrium shapes of small platinum and palladium clusters

The embedded atom method (EAM) was used to determine the equilibrium shapes of small platinum and palladium clusters (N=5–60 atoms). The stability of various polyhedral symmetries was performed at 0K. A search for the presence of any other lower energy structures was also carried out. Pt clusters reconstructed to lower energy clusters even at the magic numbers. Pd also reconstructed to lower energy structures except at the magic number sizes where the icosahedron was found to be the most stable.     

Effect of mixed organic solvents on atomic absorption spectrophotometry of refractory metals

The effect of various organic solvents on the absorption characteristics of vanadium was studied in fuel-rich oxy-acetylene and nitrous oxide-acetylene flames. The absorption of the 3183.9 Å line of vanadium was greatly enhanced by the use of various mixed organic solvents when fed to oxy-acetylene flames. In the case of the nitrous oxide-acetylene flame, the addition of diethylene glycol (about 8% in the final solution) and similar compounds to the aqueous solution of vanadium increased the absorption by about 50%. The observations and the possible role of the mixed organic solvents are discussed.     

Polymer-supported approach for solution-phase synthesis of cysteine trap protease inhibitors: procedure for straightforward optimization of the P1-P1' pocket

Peptide-based reversible and irreversible cysteine proteases inhibitors are well reported in the literature. Many of these compounds have an electrophilic carbonyl group as a cysteine trap in the place of a scissile amide moiety of the natural substrate. As a common mechanism strategy, we have designed a probe library of a cysteine trap for rapid optimization of P1-P1' pockets of different cysteine proteases. The synthesis of this library using a straightforward methodology based on polymer-supported reagents and scavengers to avoid tedious purification steps has been achieved. For the selective monobromination of diazo ketones, preparation of a new supported reagent, piperidinoaminomethylpolystyrene hydrobromide, is also described.     

Specific method for the determination of ozone in the atmosphere

A simple, sensitive and specific method for the determination of ozone in the atmosphere is described. Reactions of ozone with several 1-alkenes were studied at room temperature (25°). Eugenol(4-allyl-2-methoxyphenol), when reacted with ozone, was found to produce relatively large amounts of formaldehyde compared to other 1-alkenes tested. The method described was compared with alkaline iodide method for the determination of various concentrations of ozone in the range 0.05–2.0 p.p.m. Hydrogen peroxide, peracetic acid, sulfur dioxide and various reducing agents commonly present in the air, do not interfere. Formaldehyde when present in the air, must be determined simultaneously and the concentration of formaldehyde subtracted from that of the ozone. Any formaldehyde monitoring equipment can be easily adapted for the determination of ozone.