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A thermodynamic model calculating the solubility of hydrogen sulfide (H 2 S) in pure water and in aqueous NaCl solutions (0-6 M, 273-500 K, 0-200 bar) is presented. The model is based on a specific particle interaction theory for the liquid phase and a highly accurate equation of state for the vapor phase. With this specific interaction approach, this model is able to predict H 2 S solubility in other systems, such as H 2 S-H 2 O-Na 2 SO 4 , H 2 S-H 2 O-CaCl 2 , H 2 S-H 2 O-KCl, and H 2 S-seawater, without fitting experimental data from these systems. Comparison of the model predictions with experimental data indicates that the model is within or close to experimental uncertainty, which is about 7% in H 2 S solubility. The model is programmed and can be downloaded from the website: www.geochem-model.org/programs.htm. Online calculation is also made available on the website: www.geochem-model.org/models.htm. The H 2 S solubility model can be used together with numerical speciation-solubility modeling codes such as PHREEQC to calculate sulfide mineral solubility in H 2 S saturated brines. An example calculation for galena solubility is given.

Clinical need for treating allergic conjunctivitis (AC) is rapidly increasing. However, AC-relevant anti-inflammatory compounds are generally difficult to solubilize in water, thus limiting their therapeutic potential. Solubility-improved eye drop formulations of these compounds have poor bioavailability and a short retention time in ophthalmic tissues. Herein, we report a DNA/poly­(lactic-co-glycolicacid) (PLGA) hybrid hydrogel (HDNA) for water-insoluble ophthalmic therapeutic delivery. PLGA pre-encapsulation enables loading of water-insoluble therapeutics. HDNA’s porous structure is capable of sustained delivery of therapeutics. Dexamethasone (DEX), with demonstrated activities in attenuating inflammatory symptom in AC, was used as a model system. The designed HDNA hybrid hydrogels significantly improved the DEX accumulation and mediated the gradual DEX release in ophthalmic cells and tissues. Using the HDNA–DEX complexes, potent efficacy in two animal models of AC was acquired. Given this performance, demonstrable biocompatibility, and biodegradability of DNA hydrogel, the HDNA-based ophthalmic therapeutic delivery system enables novel treatment paradigms, which will have widespread applications in the treatment of various eye diseases.

The SAFT-LJ equation of state improved by Sun and Dubessy (2010) can represent the vapor-liquid equilibrium and PVTx properties of the CO 2 -H 2 O system over a wide P-T range because it accounts for the energetic contribution of the main types of molecular interactions in terms of reliable molecular based models. Assuming that NaCl fully dissociates into individual ions (spherical Na + and Cl À ) in water and adopting the restricted primitive model of mean spherical approximation to account for the energetic contribution due to long-range electrostatic forces between ions, this study extends the improved SAFT-LJ EOS to the H 2 O-NaCl and the CO 2 -H 2 O-NaCl systems at temperatures below 573 K. The EOS parameters for the interactions between ion and ion and between ion and water were determined from the mean ionic activity coefficient data and the density data of the H 2 O-NaCl system. The parameters for the interactions between ion and CO 2 were evaluated from CO 2 solubility data of the CO 2 -H 2 O-NaCl system. Comparison with the experimental data shows that this model can predict the mean ionic activity coefficient, osmotic coefficient, saturation pressure, and density of aqueous NaCl solution and can predict the vapor-liquid equilibrium and PVTx properties of the CO 2 -H 2 O-NaCl system over the range from 273 to 573 K, from 0 to 1000 bar, and from 0 to 6 mol/kg NaCl with high accuracy.

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