Two-photon laser spectroscopy of the muonium 1S–2S transition

The 1² S _1/2(F=1)?2² S _1/2(F=1) energy interval in muonium has been investigated by Doppler-free two-photon laser spectroscopy. The transition was observed by uniquely identifying and counting the muons released after the photoionization of the 2S state by the same laser field. The measured transition frequency of 2455 528016(58)(43) MHz is in good agreement with QED calculations. The experiment can be interpreted as a test of the Lamb shift contributions at the 1% level. The method is also well suited for a precise determination of the mass of the positive muon in a muoniumhydrogen isotope shift measurement.     

The determination of organochlorine pesticides and polychlorinated biphenyls by combustion tube decomposition and molecular emission cavity analysis

The determination of microgram quantities of chlorine in polychlorinated biphenyls and organochlorine insecticides by molecular emission cavity analysis is described. Samples either pure, in admixture or mixed with sand were decomposed at 900 ± 50°C in a quartz combustion tube in a humidified oxygen atmosphere. The products of decomposition were bubbled through water or 1% ammonia and 4-μl aliquots of the solution obtained were injected into a stainless steel indium-lined cavity and heated in a nitrogen/hydrogen flame. The chlorine was quantified by comparing the intensity of the InCl emission at 360 nm with that obtained from hydrochloric acid standards. The effect of potential interferences such as alkali and alkaline earth metals, nitrogen, phosphorus, sulphur, carbon aluminium and iron were studied. Except for the alkali and alkaline earth elements, the recoveries of the compounds burned were not affected. Where the elements interfered, methods for eliminating the interferences are described. The chlorine recovery was usually >90%.     

Synthesis of N-(2-Hydroxy-1-phenoxyacetyl)- prolylproline and Related Cation Binding and Molecular Mechanics Studies

The synthesis of N-(2-hydroxy-1-phenoxyacetyl)prolylproline 2 from 2-acetoxyphen-oxyacetic acid is described. A firstsynthesis led toN-(2-acetoxy-1-phenoxyacetyl)prolylproline methylester 8b that fragmented upon attempted esterhydrolysis with 1N NaOH. A second synthesis gave thecorresponding benzyl ester 13, which wasconverted to 2 by deacylation of the phenolicacetoxy group with pyrrolidine followed byhydrogenolysis of the ester. Cation binding by 2 in methanol and related molecular mechanics (MM)geometric optimizations are discussed.     

Prioritising highway accident sites: a data envelopment analysis model

This paper presents an optimisation procedure for prioritising highway accident sites. The methodology (data envelopment analysis) takes into account the multidimensional nature of the problem. Specifically, it recognises that different accident types on a road section should be credited with different weights, but permits such weights to vary (within reasonable limits) from section to section. The methodology also permits the inclusion of multiple inputs on the resource side, including not only the cost of repair, but factors such as driver inconvenience.     

Determination of polycyclic aromatic hydrocarbons in tobacco smoke

Improvements have been described in the apparatus and methods employed in determining polycyclic aromatic hydrocarbons in tobacco smoke by alumina-column chromatography and automatic ultra-violet spectrophotometry