The spectra of the Sloan Digital Sky Survey (SDSS) are being used to construct a catalogue of QSO absorption lines, for use in studies of abundances, relevant radiation fields, number counts as a function of redshift, and other matters, including the evolution of these parameters. The catalogue includes intervening, associated, and BAL absorbers, in order to allow a clearer definition of the relationships between these three classes. We describe the motivation for and the data products of the project to build the SDSS QSO absorption line catalogue.

Research into polymers began slowly. While polymers have long been considered to be very useful materials, today they are receiving greater recognition as subjects for conducting good science.

A series of Main-chain liquid crystalline polymers with long and polydisperse soft segments has been synthesized. The thermal properties of these polymers have been characterized by differential scanning calorimetry, optical microscopy and wide angle X-ray diffraction. Unexpectedly, these polymers have a strong tendency to form purely smectic Mesophases. The degree of ordering of these polymeric mesophases is Much higher than that of the mesophase formed by a low molecular weight Model compound with the same Mesogen. The soft segment length effects on thermal behavior of such segmented copolymers have been elucidated. A semi-quantitative theory has been formulated to interpret these observations. A phase diagram relating thermal properties to soft segment length has been proposed.

Binary polymer blends in which one or both components crystallize have been considered. These May be miscible or immiscible in the amorphous state, and phase separation may occur along with crystallization. The rates of these two processes vary differently with temperature, so the consequent morphology and properties depend upon the temperature history. For Miscible blends, the glass transition temperature depends upon composition. This affects diffusion so that crystallization kinetics varies as composition changes. If only one component crystallizes and the other is rejected, this rejected component diffuses away from the growing crystalline regions in a manner dependent upon the interaction between components.

These phenomena are studied using a variety of techniques such as calorimetry, x-ray diffraction and scattering, and small-angle light and neutron scattering for a number of polymer systems.

Rheo-optical studies on aligned and unaligned melts of a main chain thermotropic polyester with flexible spacers are discussed in terms of the predictions of the Ericksen-Leslie equations. It is shown, using conoscopy, that the director is flowaligning at temperatures close to TNI and nonflow-aligning close to a smectic to nematic (TSN) phase transition. The implications of these results are discussed in terms of the change in sign of one of the Leslie viscosity coefficients and interpreted in the framework of the Ericksen-Leslie Theory.

Polymer solutions comprising stiff-chain polyester and flexible polysulfone were examined via light scattering techniques. Results were analyzed using the Stein-Wilson extension of the Debye-Bueche theory, in which the correlation lengths due to orientation fluctuations and mean-squared fluctuations of the molecular anisotropy were obtained. For a molecular dispersion, the correlation length is small and a function of concentration; as the anisotropy is attributed to the rod molecules. Aggregation of rods is associated with an increase in the magnitude and size of the density fluctuations, and a change in anisotropy fluctuations is dependent on the degree of orientation correlation of the rods in the aggregate. Blends prepared by solution casting were studied by a small-angle light scattering method. Results thus far demonstrate that aggregates are present in most of the rod/coil composites prepared.

Neutron reflectivity has been used to determine the concentration profile at the vacuum-polymer interface for a two polymer blend. To quantify surface enrichment and evaporation due to differences in chain length, we have measured the reflectivity of a mixture of short deuterated and long protonated polystyrene chains (DPS & PS), with a weight fraction of 0.5. When a mixture of DPS and PS chains of molecular weight 720 and 910k respectively were annealed, a small but measurable increase in asymptotic reflectivity occured, coupled with a decrease of film thickness and scattering length density. This is indicative of surface enrichment and evaporation of the light chains (DPS). Ellipsometry studies confirmed that the short chains evaporated and its rate was established as a function of the temperature. Upon increasing the DPS molecular weight to 9600, the enrichment becomes considerably greater whilst the evaporation becomes negligible.

The scattered amplitude from a collection of objects, each small as compared with the wavelength of the radiation, is given by