Controlling the pore connectivity of polymer foams is key for most of their applications, ranging from liquid uptake, mechanics, and acoustic/thermal insulation to tissue engineering. Despite their importance, the scientific phenomena governing the pore‐opening processes remain poorly understood, requiring tedious trial‐and‐error procedures for property optimization. This lack of understanding is partly explained by the high complexity of the different interrelated, multiscale processes which take place as the foam transforms from an initially fluid foam into a solid foam. To progress in this field, this work takes inspiration from long‐standing research on liquid foams and thin films to develop model experiments in a microfluidic “Thin Film Pressure Balance.” These experiments allow the investigation of isolated thin films under well‐controlled environmental conditions reproducing those arising within a foam undergoing cross‐linking and drying. Using the example of alginate hydrogel films, the evolution of isolated thin films undergoing gelation and drying is correlated with the evolution of the rheological properties of the same alginate solution in bulk. The overall approach is introduced and a first set of results is presented to propose a starting point for the phenomenological description of the different types of pore‐opening processes and the classification of the resulting pore‐opening types.
A simple, sensitive and reproducible spectrophotometric method is developed for determining the pregabalin (PGB) content in bulk and in capsule dosage form using an experimental design approach. The proposed method is based on the condensation reaction of PGB (primary amine) with p-dimethylaminobenzaldehyde (PDAB) in an acidic medium to form a PGB-PDAB complex. The PGB-PDAB complex shows maximum absorption at 395.80 nm. The proposed method is validated according to the ICH Q2 (R1) guidelines for validation of analytical methods. The percentage purity of PGB in capsule dosage form as determined using the proposed method is 100.05 ± 1.48 whereas the corresponding value by the official method (Indian Pharmacopoeia, 2010) is 100.46 ± 0.41. The t-value and F-value are calculated for statistical comparison and are found to be 0.60 and 0.08, respectively. The proposed method may recommend for routine quality control analysis of PGB in its pharmaceutical dosage form. ª 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of University of Bahrain. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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