Background Recent studies have shown that Gaviscon Double Action Liquid (a combination alginate-antacid) administered postprandially co-localizes with the acid pocket, the ‘reservoir’ for postprandial acid reflux. Aim This study compared the effectiveness of Gaviscon Double Action Liquid to an equivalent strength antacid without alginate in controlling postprandial acid reflux in GERD patients. Methods 14 GERD patients undertook two 3.5-hour high-resolution manometry/pH-impedance studies during which they ate a standardized meal. In a double-blinded randomized crossover design they then took Gaviscon or CVS brand antacid, each with ~18 mmol/l acid neutralizing capacity. The primary outcome was distal esophageal acid exposure; secondary outcomes were number of reflux events, proximal extent of reflux, nadir pH of the refluxate, mechanism of reflux, and reflux symptoms scored with a validated instrument. Results 10 patients completed the study. Gaviscon studies had significantly less distal esophageal acid exposure and greater nadir refluxate pH in the 30–150 minute postprandial period than antacid studies. There were no differences in the number of reflux events (acid or weakly acidic) or the number of proximal reflux events (15–17 cm above the LES) with either study medication. Conclusions Gaviscon Double Action Liquid was more effective than an antacid without alginate in controlling postprandial esophageal acid exposure. However, the number and spatial distribution of reflux events within the esophagus were similar. This suggests that Gaviscon main effectiveness related to its co-localization with and displacement/neutralization of the post-prandial acid pocket, rather than preventing reflux.

The microstructure of (001)p-oriented (subscript p indicates the choice of a pseudocubic unit cell) potassium niobate (KNbO3) thin films grown by metalorganic chemical vapor deposition on (100)p lanthanum aluminate and having a large second-order nonlinear optical response is examined. Transmission electron microscopy reveals the films to be epitaxial and the film/substrate interface to be abrupt and semicoherent. The strain between the film and substrate due to the 5% lattice constant mismatch is accommodated by formation of an array of misfit dislocations as well as 60° and 120° ferroelectric microdomains. The domains are located in a 20 nm thick region adjacent to the interface. Beyond the multidomain region, the film is free of significant defects.

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