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Betaine surfactants are used widely in oil field chemistry as well as other industrial applications, but their foaming ability is very poor so that it cannot be used in foaming. In this work, the effect of octadecyl ammonium oxide on the foam properties of oleate amide propyl betaine, a new compound foaming reagent, is studied based on foam performance. Then, a foam drainage reagent of 0.5 wt% oleate amide propyl betaine and 0.1 wt% octadecyl ammonium oxide is developed for natural gas production. Its salt resistance, methanol resistance, high temperature resistance, anti-condensate oil performance, and emulsification ability are systematically evaluated. Furthermore, the factors affecting foam performance are analyzed. The results show that the compound foaming reagent has good anti-salt, anti-methanol, and anti-condensate oil properties for meeting application requirements. The microstructures of foams derived from different reagents reveal the stability mechanism. All results reflect the fact that compounding can expand their application range in different environments to various extents, which benefits the design and use of compound surfactants.

Peptide-sandwiched mesohemes (PSMs), a class of synthetic hemoprotein models, have been developed to look at the impact of heme-protein interactions on hemoprotein structure and function. Each PSM, numbered 1 to 5, is made up of two identical peptides covalently connected to the propionate groups of iron(III) mesoporphyrin IX through amide linkages with lysine (Lys) N-epsilon amines. In the folded forms of 1,2,4 and 5, both peptides adopt conformations with varying degrees of alpha-helix content. The folded forms of 3 and 5 were found to be less stable than the folded forms of 1, 2 and 4, even when 2,2,2-trifluoroethanol or 1-propanol are added to boost the helicity of the peptides.

UV/vis titrations enable the determination of equilibrium constants for the formation of complexes between three types of porphyrins and 23 different ligands. Analysis of the ring currents of the porphyrin by NMR enables the determination of the solution structures of the complexes. NMR data reveal that the edge-to-face conformation contributes little to the binding energies in the complexes. A comparative study helps evaluate the contributions of stacking and ionic binding to the total binding energy. van der Waals forces, rather than solvophobic forces, induce the stacking.

A new procedure enables the preparation of eleven new porphyrins bearing ammonium side chains, including five water-soluble porphyrins. UV/vis titrations enable the determination of porphyrin core protonation. The viscosity of ds-calf thymus DNA is decreased by the water-soluble porphyrins while the melting point of DNA is enhanced by them. Experimental data reveal the absence of intercalation in the DNA-porphyrin interaction. The high binding-affinity between DNA and porphyrin indicates the existence of groove binding.

The production of the wells in well group Mimosa-4 of Mimosa4 block of Borger Basin in Chad is very low due to reservoir damage while drilling and completion. Acidizing is most wildly applied and successful technology to remove practical plug in sand reservoir and increase production. But it cannot be applied in Chad for the import restriction of fluid acid. While the physical plugging remove technologies shows no satisfying results, Solid acid system is proposed in the paper to remove reservoir plugging in the well group and the formula is suggested based on laboratory experiments. [ABSTRACT FROM AUTHOR]