Interpretation of analytical chemical information by pattern recognition methods-a survey

Since the late sixties, pattern recognition techniques have been used by analytical chemists to facilitate the interpretation of multivariate analytical information. Most research within the field has focused on adapting pattern recognition methods to chemical data. This has been necessary since chemical data are often complicated by the fact that distributions are unknown. Through the first decade of chemical pattern recognition, promising results have been obtained even though the data sets studied have frequently been rather small for statistical analysis. The past few years have shown that an increasing number of analytical chemists are interested in the sheer utility of pattern recognition. This can be taken as a valid sign of a useful approach. The present communication surveys this development. Those methods which have proved most useful for analytical chemical data are described in some detail, and applications within the various fields of analytical chemistry are reviewed.     

Synthetic protocols and building blocks for molecular electronics

Simple and readily accessible aryl bromides are useful building blocks for thiol end-capped molecular wires. Thus, 4-bromophenyl tert-butyl sulfide and 1-bromo-4-(methoxymethyl)benzene serve as precursors for a variety of oligo(phenylenevinylene) and oligo(phenyleneethynylene) wires via efficient synthetic transformations as presented in this paper.     

Fulleropyrrolidine end-capped molecular wires for molecular electronics--synthesis, spectroscopic, electrochemical, and theoretical characterization

In continuation of previous studies showing promising metal-molecule contact properties a variety of C(60) end-capped "molecular wires" for molecular electronics were prepared by variants of the Prato 1,3-dipolar cycloaddition reaction. Either benzene or fluorene was chosen as the central wire, and synthetic protocols for derivatives terminated with one or two fullero[c]pyrrolidine "electrode anchoring" groups were developed. An aryl-substituted aziridine could in some cases be employed directly as the azomethine ylide precursor for the Prato reaction without the need of having an electron-withdrawing ester group present. The effect of extending the π-system of the central wire from 1,4-phenylenediamine to 2,7-fluorenediamine was investigated by absorption, fluorescence, and electrochemical methods. The central wire and the C(60) end-groups were found not to electronically communicate in the ground state. However, the fluorescence of C(60) was quenched by charge transfer from the wire to C(60). Quantum chemical calculations predict and explain the collapse of coherent electronic transmission through one of the fulleropyrrolidine-terminated molecular wires.     

Computerized electroanalysis : Multiple scanning anodic stripping and its application to sea water

the determination of copper, lead, zinc, cadmium and bismuth in standard sea water samples by multiple scanning anodic stripping has been investigated. The influence of plating potential and sample pH has been studied.     

Multistep scattering in the 160 MeV208Pb(α, α′) reaction

New experimental data has been obtained for the²⁰⁸Pb(α, α′) reaction induced by 160 MeV alpha particles, for inelastic scattering to forward angles. We use these data to investigate the applicability of the multistep scattering theory of Feshbach, Kerman, and Koonin for describing this reaction. The mechanism we study, following the work of Gadioli et al. [1], is of the incident alpha particle remaining intact throughout the scattering process, exciting nucleon particle-hole pairs through multistep process. We conclude that this mechanism, combined with compound nucleus decay at low emission energies, can account for much of the observed data. However, there are indications that other processes also contribute at energies above the compound nucleus emission regime, and we outline future theoretical analyses that are needed.