With the aim of improving the solubility of ciprofloxacin, polybasic organic acids were utilized to react with ciprofloxacin in different stoichiometric proportions. The use of the solvent drop grinding (SDG) method, as well as the solvent evaporation method, resulted in the crystalline salts ciprofloxacin/fumaric acid (1:1, 2:1), ciprofloxacin/maleic acid (1:1) and ciprofloxacin/citric acid (2:1). The solubilities of these salts in pure water (pH 7.0) were determined using high-performance liquid chromatography (HPLC) at 310 K, with the salts showing considerably greater solubility than ciprofloxacin itself and, interestingly, ciprofloxacin/fumaric acid (2:1) being more soluble than ciprofloxacin/fumaric acid (1:1). Intrigued by this phenomenon, we undertook a comparison of the crystal structures of the salts: the three-dimensional sandwich-like structure observed in the 2:1 salt indicates that the preferred stacking may be a factor in increasing the solubility of ciprofloxacin.
Multi-objective optimization linked with an urban stormwater model is used in this study to identify cost-effective low impact development (LID) implementation designs for small urbanizing watersheds. The epsilon-Non-Dominated Sorting Genetic Algorithm II (ε-NSGAII) has been coupled with the US Environmental Protection Agency's Stormwater Management Model (SWMM) to balance the costs and the hydrologic benefits of candidate LID solutions. Our objective in this study is to identify the near-optimal tradeoff between the total LID costs and the total watershed runoff volume constrained by pre-development peak flow rates. This study contributes a detailed analysis of the costs and benefits associated with the use of green roofs, porous pavement, and bioretention basins within a small urbanizing watershed in State College, Pennsylvania. Beyond multi-objective analysis, this paper also contributes improved SWMM representations of LID alternatives and demonstrates their usefulness for screening alternative site layouts for LID technologies.
This
paper elucidated eight crystal structures of acotiamide hydrochloride
(AH) via single-crystal X-ray diffraction (SCXRD) with water (1AH-1W-I,
1AH-3W), methanol (1AH-1M), methanol and water (1AH-1W-1M-I, 1AH-1W-1M-II),
ethanol (1AH-1E), ethanol and water (1AH-1W-1E), and n-propanol (1AH-1P). Two influencing factors, water content and solvent
type, were investigated for their effects on the formation of distinct
hydrates and solvates. In addition, the stability and solubility of
these solid phase forms were analyzed based on their structures. The
results of SCXRD revealed that AH tends to crystallize together with
a solvent as both a hydrogen bond donor and acceptor. The control
experiments in methanol–water, ethanol–water, n-propanol–water, and acetone–water systems
showed that the final crystal form varied with an increase in the
water content. The eight crystals fall into three types based on their
spatial stacking, corresponding interestingly to different stability
and solubility. Furthermore, the relationship between changes in solubility
curves and the solid phase forms of the undissolved samples was preliminarily
elucidated.
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