Isothermal mutual diffusion coefficients (interdiffusion coefficients) were measured for ternary aqueous mixtures of NaCl and Na2SO4 at a constant NaCl molarity fraction z 1 = 0.9000 at 298.15 K, using high precision Rayleigh interferometry with computerized data acquisition. The experiments were performed at total molarities of (2.0000, 3.0003, 4.0010, and 5.0071) mol·dm-3. Diffusion coefficients of NaCl(aq) were also measured at essentially these same four concentrations, those of Na2SO4(aq) at (1.3500 and 1.6998) mol·dm-3, as were the densities of all solutions. These measurements supplement our earlier ones at total molarities of (0.5000, 1.00025, and 1.4990) mol·dm-3 with various ratios of NaCl to Na2SO4, which also included compositions with z 1 = 0.9000. At nearly all of the ternary solution compositions, the Na2SO4 cross-term diffusion coefficient is small and negative whereas the NaCl cross-term diffusion coefficient is larger and positive. However, at the fixed NaCl molarity fraction z 1 = 0.9000, the Na2SO4 cross-term diffusion coefficient changes from negative to positive values as the total concentration exceeds about 4.0 mol·dm-3, and above 3.0 mol·dm-3 the size of the NaCl cross-term diffusion coefficient exceeds that of the corresponding Na2SO4 main-term diffusion coefficient. This indicates that, at high concentrations, a concentration gradient of Na2SO4 causes the transport of more NaCl than of itself. In contrast, cotransport of Na2SO4 by a concentration gradient of NaCl is quite small.

In recent years, considerable efforts have been made for the development of multifunctional nanoparticles with diagnosis and therapy functions. To achieve enhanced CT imaging and photothermal therapy on the tumor, we employed iodinated nanoparticles as template to construct Au nanoshell structure and demonstrated a facile but effective approach to synthesize biocompatible and well-dispersed multifunctional nanoparticles by coating iodinated nanoparticles with Au nanoshell and subsequent surface modification by hyaluronic acid. The resultant poly(2-methacryl(3-amide-2,4,6-triiodobenzoic acid))/polyethylenimine/Au nanoshell/hyaluronic acid (PMATIB/PEI/Au nanoshell/HA) nanoparticles had relatively high X-ray attenuation coefficient and photothermal efficiency. After intravenous injection into MCF-7 tumor-bearing mice, PMATIB/PEI/Au nanoshell/HA nanoparticles were efficiently accumulated in the tumor, remarkably enhanced the tumor CT imaging, and selectively ablated the tumor through the thermal treatment of lesions under the NIR irradiation. Thus, PMATIB/PEI/Au nanoshell/HA nanoparticles displayed a great potential for CT diagnosis and CT-guided, focused photothermal tumor therapy.

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Isothermal mutual diffusion coefficients (interdiffusion coefficients) and refractive index increments were measured for ternary aqueous mixtures of NaCl and Na2SO4 at constant NaCl molarity fraction z 1 = 0.9500 at 298.15 K, using high precision Rayleigh interferometry with computerized data acquisition. The densities of these solutions were measured using vibrating tube densimetry. The experiments were performed at seven total molarities ranging from (0.499 92 to 4.978 34) mol·dm-3. These measurements supplement our earlier ones at other compositions and composition fractions. The Na2SO4 cross-term diffusion coefficient D 21 is small and negative at nearly all of the ternary solution compositions, whereas the NaCl cross-term diffusion coefficient D 12 is larger and positive. However, at z 1 = 0.9500, D 21 changes sign as the total concentration exceeds 4.3 mol·dm-3, and above 3.2 mol·dm-3 the value of D 12 exceeds that of the corresponding Na2SO4 main-term diffusion coefficient D 22. Thus, at high concentrations, a concentration gradient of Na2SO4 causes the transport of more NaCl than of itself. At each fixed total concentration, extrapolation of Na2SO4 main-term diffusion coefficients from these and our earlier results, to zero concentration fraction of Na2SO4 (i.e., z 1 → 1), yielded the trace diffusion coefficient of the SO4 2- ion D tr(SO4 2-) in NaCl(aq). Comparing these D tr(SO4 2-) values in NaCl(aq) to published D tr(SO4 2-) values in Na2SO4(aq) shows agreement to 1−8%, when the comparisons are made at equal volumetric ionic strength. Similar extrapolations of the volumetric and refractive index increment results yielded the trace partial molar volume and trace refractive index increment, respectively. Densities of NaCl(aq) at 298.15 K were critically reanalyzed.

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