Chain conformations and the presence of chain overlaps and entanglements in dilute polymer solutions have been analyzed. The fundamental problem of existence of chain overlaps in dilute solutions is related to the drag reduction phenomenon (DR). Even though DR occurs in solutions with the concentration of only few parts per million (ppm), some theories suggest that entanglements may play an important role in DR mechanism. Brownian dynamics technique have been used to perform simulations of dilute polymer solutions at rest and under shear flow. A measure of interchain contacts and two different measures of entanglements have been devised to evaluate the structure of polymer chains in solution. Simulation results have shown that overlaps and entanglements do exist in static dilute solutions as well as in solutions under shear flow. The effect of solution concentration, shear rate and molecular mass have been examined. In agreement with the solvation theory of DR mechanism, simulation results have demonstrated the importance of polymer + polymer interactions in dilute solutions.

The Kinetics of the reactions involving alkyl and silyl hydrides were studied by the flash photolysis / resonance fluorescence technique. The reactions of alkyl radicals (R = C₂H₅, i-C₃H₇, t-C₄H₉) with HBr have been studied at room temperature and the rate constants obtained (units are in cm³ s^-1 ) are: k₃.₃ = (7.01 ± 0.15) x 10^-12, k₃.₂ = (1.25 ± 0.06) x 10^-11, k₃.₁ = (2.67 ± 0.13) x 10^-11 These results, combined with previously determined reverse rate constants and other kinetic information, yield bond dissociation enthalpies (units in kJ mol^-1) at 298 K : primary C-H in C₂H₅-H (423.6 ± 2), secondary C-H in i-C₃H₇-H (409.9 ± 2), tertiary C-H in t-C₄H₉-H (405.1 ± 2). These rate constants and bond energies are in good agreement with previous results.

This study examines the waste of cotton gins as a potential alternative energy source, on account of its heat content, availability, and low emission rates. To confirm that this potential energy source meets minimum industrial fuel standards, this research has carried out an investigation of some important physical characteristics and toxic element analysis of cotton gin waste. Using cotton gin waste as fuel is an attractive solution to the problems of disposing of a surplus agricultural waste as well as supplementing fuel must meet both environmental emission standards and industrial fuel standards, the physical and chemical characteristics of cotton gin waste and its toxic element concentrations are important for its objective evaluation as a fuel. Constituent components, moisture contents, and ash contents of four separate parts of cotton gin waste were determined and evaluated closely following the American Society for Testing and Materials (ASTM) test methods. The three most toxic heavy metals, Arsenic (As), Chromium (Cr), and Lead (Pb), chosen for quantitative analysis were determined by using an inductively coupled plasma atomic emission spectrometry and a microwave oven sample digestion method.