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Steady-state fluorescence, time-resolved fluorescence quenching, and isothermal titration microcalorimetry have been used to study the interactions of cationic gemini surfactants alkanediyl-alpha,omega-bis(dodecyldimethylammonium bromide) (C(12)C(S)C(12)Br(2), S = 3, 6, and 12) with hydrophobically modified poly(acrylamide) (HMPAM) and unmodified poly(acrylamide) (PAM). Without addition of gemini surfactant, 0.2 wt % HMPAMs except PAM have already self-aggregated into hydrophobic aggregates. Different from single-chain surfactants, C(12)C(S)C(12)Br(2) have stronger interactions with HMPAMs to form surfactant/polymer aggregates, even with PAM. Addition of C(12)C(S)C(12)Br(2) may cause the disruption of HMPAM hydrophobic aggregates and the formation of mixed micelles. It is found that HMPAMs generate lower micropolarity of mixed micelles, larger values of enthalpy of interaction (DeltaH(ps)), and nearly constant values of Gibbs free energy of interaction (DeltaG(ps)). On the other hand, C(12)C(S)C(12)Br(2) with longer spacer brings out slightly lower micropolarity of mixed micelles, owing to the lower electrostatic repulsion between surfactant headgroups. Especially for C(12)C(12)C(12)Br(2), the values of DeltaH(ps) are much more endothermic and the values of DeltaG(ps) are much less negative. The weaker interactions of C(12)C(12)C(12)Br(2) with HMPAMs arise from the marked reduction of attraction between surfactant headgroups and polymer hydrophilic groups induced by its longer spacer.

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Ultrafine fish bone powder (UFBP) from silver carp (Hypohthalmichthyxtitrix molitrix) was prepared using dry media milling. The characteristics of UFBP were investigated by laser particle size analyzer, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), and inductively coupled plasma (ICP) spectrometry. The size and specific surface area of UFBP particles were significantly (p<0.05) affected by rotation speed, media/powder weight ratio, media diameter, and milling time. With the following conditions: rotation speed of 400 revolutions per minute, Downloaded by [University of Tennessee, Knoxville] at 13:38 01 June 2016A c c e p t e d M a n u s c r i p t 2 ratio of media to fish bone powder at 4:1, media diameter of 2 mm and 2.5 h of milling time, the optimal values of particle size (1.75 µm) and specific surface area (7.75 m 2 /g) were obtained.The SEM results confirmed that the particle became smaller and more uniform after milling treatment. Ash (63.71 %) and protein (20.52 %) were the main components of UFBP, and total calcium content was determined to be 236. 90 mg/g in dried UFBP. As UFBP particle size decreased, calcium solubility significantly increased (p<0.05), calcium content on the surface layer decreased, but the chemical compositions and structure did not change.