Focuses on molecular weight and molecular weight distributions (MWD) and models for predicting MWD in a pedagogical way. In addition, instrumental methods used to characterize MWD are reviewed with emphasis on physical chemistry of each, including end-group determination, osmometry, light scattering, solution viscosity, fractionation, and…

Discusses various aspects of polymeric mixtures, mixtures of structurally different homopolymers, copolymers, terpolymers, and the like. Defines concepts of polymer-polymer miscibility from practical and theoretical viewpoints, and ways of predicting such miscibility. (JN)

Describes geothermal, aerospace, and undersea applications of polymeric materials, focusing on properties needed by and forces acting on the polymers. (JN)

The properties of natural and synthetic polymeric "coatings" are reviewed, including examples and uses of such coatings as cellulose nitrate lacquers (for automobile paints), polyethylene, and others. (JN)

Topological ideas can be used to predict a variety of textures and defects in condensed matter systems under certain conditions. This article describes one means of creating and observing textures in liquid crystals which exhibit a rich variety of such textures. The results of these observations are presented. (Author/SK)

Discussed are the mechanisms of nuclear magnetic relaxation, and applications of relaxation times. The measurement of spin-lattice relaxations is reviewed. It is stressed that sophisticated techniques such as these are becoming more important to the working chemist. (CW)

Presented is an experiment to show the connection between spectroscopy and thermochemistry by examining the spectra of atomic sodium and diatomic sodium. Background information; a description of the apparatus; procedures; calculations; and energy diagrams are included. (CW)

Discussed are some of the issues which were considered when the International Union of Pure and Applied Chemistry revised its guide to notation in physical chemistry. Included are the choice between SI and non-SI units and choosing sensible names and symbols for quantities. (CW)

Applications of lasers to molecular absorption spectrometry, molecular fluorescence spectrometry, visible semiconductor fluorometry, atomic absorption spectrometry, and atomic fluorescence spectrometry are discussed. Details of the use of the frequency-doubled diode laser are provided. (CW)

Describes a set of simple, inexpensive, classical demonstrations of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) principles that illustrate the resonance condition associated with magnetic dipoles and the dependence of the resonance frequency on environment. (WRM)

We report on a computational chemistry course for undergraduate students that successfully incorporated a research project on the design of new contrast agents for magnetic resonance imaging and shift reagents for in vivo NMR. Course outcomes were positive: students were quite motivated during the whole year--they learned what was required of…

"Drosophila melanogaster" is emerging as a valuable genetic model system for the study of mental retardation (MR). MR genes are remarkably similar between humans and fruit flies. Cognitive behavioral assays can detect reductions in learning and memory in flies with mutations in MR genes. Neuroanatomical methods, including some at single-neuron…

Details ab initio crystal orbital calculations using all-trans-polyethylene as a model. Describes calculations based on various forms of translational symmetry. Compares these calculations with ab initio molecular orbital calculations discussed in a preceding article. Discusses three major approximations made in the crystal case. (CW)

In this article, the third part of a series, the results of ab initio polymer calculations presented in part 2 are discussed. The electronic structure of polymers, symmetry properties of band structure, and generalizations are presented. (CW)

Discusses the difficulties that some students have in understanding the concept of chemical reactions. Proposes that instructors try to consider the various difficulties during a chemistry course when students form their concepts of element conservation. (TW)