No abstract

In order to explain the difference in theta temperatures between ring-shaped polymers and their corresponding linear polymers, the Huggins parameter x of ring-shaped polymers is assumed to obey the dependence x = x1 (1 + 0 Q2) on local segment concentration as expressed by the volume fraction of the polymer @ 2 , and 0 being a constant. A comparison between theoretical results and light scattering measurements of Roovers and ourselves is satisfactory.

Relationships between the ratios of the mean-square radii of gyration g, and the second virial coefficients gA, of ring-shaped and linear polymers with the degree of polymerization P of the polymer and its Peterlin exponent E in dilute solution were derived theoretically and numerical values calculated. The second virial coefficients of ring-shaped and of linear polystyrene at 25 "C in toluene were determined using light scattering. By verifying the theoretical calculation based on the experimental determination of this polymer-solvent system with light scattering and other methods reported in the literature, the agreement between theoretical calculation and experimental results is shown. The correlation equations for linear (1) and ring-shaped (r) polystyrene in toluene at 25 "C A*,, = 8,06.

In the bioleaching - solvent extraction - electrowinning practices for copper extraction, the solvent extraction process is used to enrich the copper in the leachate to a high lever to make the sequent electrowinning process possible. O/W type of interfacial emulsion always forms at the interface between organic phase and aqueous phase in the solvent extraction practices. Diversified microorganisms were discovered by microscope growing in the interface emulsion of copper solvent extraction. The diversity of them was analyzed by using 16s rRNA gene sequencing. It was indicated that there exist seven categories of bacteria in the interface emulsion, among which common bioleaching bacteria, such as Leptospirillum sp.,Acidithiobacillus ferrooxidans, Metallibacterium sp., are included. The dominant strains are Leptospirillum sp. E4-L9 and Acidithiobacillus ferrooxidans ATCC 23270, which account up to 40.48 % and 38.1 %, respectively. It was uncovered that bioleaching bacteria can be intercepted by interfacial emulsion of solvent extraction to make their population in the raffinate lower and the efficiency of bioleaching decrease consequently.