Publications by authors named "Lai Zeng"
Article Synopsis
- A new form of the drug piracetam, called Form VI, has been identified and analyzed using various techniques like X-ray powder diffraction and infrared spectroscopy, showing a unique characteristic peak at 24.2° (2θ).
- Form VI is metastable compared to earlier forms (Form II and Form III), converting to Form II in ethanol within 15 minutes, while remaining stable in isopropanol for over 6 hours.
- Experiments with piracetam in ethanol and isopropanol solutions showed that Form VI predominates at lower temperatures, while higher temperatures favor Form II, indicating that nucleation is easier in ethanol due to lower energy barriers.
Article Synopsis
- The solid-liquid solubility of two polymorphs of a compound was measured in n-propanol using both isothermal and low heating rate methods, with the latter showing superior results due to differences in crystal settling.
- Experimental results indicate that FII is the stable polymorph across a temperature range of 268 K to 308 K.
- The solubility data was successfully correlated and predicted to the melting point using a semi-empirical regression model, revealing a positive deviation from Raoult's law, where solute activity coefficients decreased with rising temperatures.
The solubility of butamben has been measured gravimetrically in pure methanol, 1-propanol, 2-propanol, 1-butanol, and toluene over the temperature range 268-298 K. Polymorph transition and melting temperatures, associated enthalpy changes, and the heat capacity of the solid forms and the supercooled melt have been measured by differential scanning calorimetry. Based on extrapolated calorimetric data, the Gibbs energy, enthalpy and entropy of fusion, and the activity of solid butamben (the ideal solubility) have been calculated from below ambient temperature up to the melting point.
View Article and Find Full Text PDFHerein we report a one-step method to prepare high internal water-phase double emulsions (W/O/W) via catastrophic phase inversion of water-in-oil high internal phase emulsions (W/O HIPEs) stabilized solely by 12-acryloxy-9-octadecenoic acid (AOA) through increasing the content of water phase. This is the first time for double emulsions to be stabilized solely by a single small molecular surfactant, which are usually costabilized by both hydrophilic and hydrophobic surfactants. After neutralized with ammonia, AOA is confirmed to be capable of stabilizing both W/O emulsions and O/W emulsions, which may account for its unique ability to stabilize double emulsions.
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